__MoEClust: Gaussian Parsimonious Clustering Models__   
=======================================================
__with Gating and Expert Network Covariates__ 
=======================================================
__and a Noise Component__
=======================================================

## MoEClust v1.5.1 - (_16<sup>th</sup> release [minor update]: 2022-12-19_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* New `MoE_gpairs` arg. `diag.pars$show.dens=FALSE` added to toggle whether  
  parametric density estimates are drawn over diagonal panels for each response  
  variable (with or without the underlying histograms; see documentation).
* New function `MoE_Similarity` added and integrated into `plot.MoEClust`.
* New function `MoE_AvePP` added.
* Minor speed-ups to `MoE_mahala` for univariate data with (default) `identity=FALSE`.

## MoEClust v1.5.0 - (_15<sup>th</sup> release [minor update]: 2022-03-28_)
### Significant User-Visible Changes
* Checks/fixes for empty components extended to components w/ `<=1` observations (or equivalent):  
__important__ --- some rare cases which previously would not converge will now converge!
* Fixed _significant_ bugs related to `exp.init$malanabis=TRUE` (the default) introduced in v1.4.1,  
__important__ --- restored correct behaviour, especially when multiple `modelNames` are being fitted!

### New Features & Improvements
* New function `MoE_entropy` added.
* Added `summary` (and related `print`) methods for `MoECriterion` objects.
* Minor speed-up to E-step for `"EEE"` & `"VVV"` models.

### Bug Fixes & Miscellaneous Edits
* Allowed `G=0:X` in `MoE_clust` without adding noise for `G>0`, unless  
specifying models w/ noise, undoing another bug introduced in v1.4.1.
* Fixed minor bug when supplying `modelNames` when `G=1` only.
* Fixed check on validity of `hc.meth` arg. in `MoE_control`.
* Minor documentation clarifications re: `z.list` in `MoE_control`.

## MoEClust v1.4.2 - (_14<sup>th</sup> release [patch update]: 2021-12-19_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* `MoE_mahala` arg. `identity` (& related `MoE_control` `exp.init$identity` option) is now also  
  relevant for univariate data: old behaviour is retained via respective defaults of `FALSE` & `TRUE` for  
  multivariate & univariate data (i.e. only ability to set `identity=FALSE` for univariate data is new).
* Fixed `MoE_clust` bug when `tau0` is specified but `G` is not (introduced in last update).
* Minor speed-up to `MoE_gpairs(response.type="density")` w/ expert covariates & noise component.
* `MoE_gpairs` arg. `density.pars$grid.size` now recycled as vector of length 2 if supplied as scalar.
* `aitken` now returns `ldiff`, the difference in log-likelihood estimates used for the stopping criterion.
* `sapply` replaced with `vapply`, with other negligible speed-ups.

## MoEClust v1.4.1 - (_13<sup>th</sup> release [patch update]: 2021-10-12_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Various further fixes to `MoE_stepwise`:  
  * Added the arg. `fullMoE` (defaulting to `FALSE`) which allows restricting the search to "full"  
    MoE models where the same set of covariates appears in both the gating & expert networks.
  * When `initialModel`/`initialG` is given, the `"all"` option for `noise.gate` & `equalPro`    
  now reverts to `"both"` whenever `"all"` would unnecessarily duplicate candidate models.
  * Small speed-up if `gating` &/or `expert` have covariates that are already in `initialModel`.
  * Small speed-up by searching `G=1` `equalPro` models w/ expert covariates only once.
  * Two fixes to handle how `initialModel` and `modelNames` interact:  
    * It's now assumed (else warned) that `initialModel` should be optimal w.r.t. model type.
    * The supplied `modelNames` are augmented with `initialModel$modelName` if needs be.
* `MoE_control` gains the arg. `exp.init$estart` so the paper's Algorithm 1 can work as intended:  
  `exp.init$estart` toggles the behaviour of `init.z="random"` in the presence of expert covariates  
  when `exp.init$mahalanobis=TRUE` & `nstarts > 1`:  when `FALSE` (the default/old behaviour), all  
  random starts are put through the initial reallocation routine and then subjected to full runs of the EM;  
  when `TRUE`, only the single best random start obtained from this routine is subjected to the full EM.
* Handled name mismatches for optional args. w/ `list(...)` defaults in `MoE_control`/`MoE_gpairs`.
* Fixed printing of `noise.gate` in `MoE_compare` for `G=1` models w/ noise & gating covariates.
* Improved checks on `G` in `MoE_clust`.

## MoEClust v1.4.0 - (_12<sup>th</sup> release [minor update]: 2021-06-21_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Various edits to `MoE_stepwise()` (thanks, in part, to requests from Dr. Konstantinos Perrakis):  
  * Added `initialModel` arg. for specifying an initial model from which to begin the search,  
  which may already be a mixture and may already include covariates, etc.
  * Added `initialG` arg. as a simpler alternative when the only available  
  prior information is on the number of components.
  * Added `stepG` arg. (defaults to `TRUE`) for fixing the number of components  
  & searching only over different covariate configurations (i.e. when `FALSE`).
  * Speedups by preventing superfluous searches for equal  
  mixing proportion models when there are gating covariates.
  * `noise.gate` arg. now also invoked when adding components to models with gating covariates  
  & a noise component (previously only when adding gating covariates to models with noise).
  * `equalPro` & `noise.gate` args. gain new default `"all"` (see documentation for details).
  * Stronger checks on `network.data` argument.
* New methods and edits related to prediction:  
  * Added `fitted` method for `"MoEClust"`objects (a wrapper to `predict.MoEClust`).
  * Added `predict`, `fitted`, & `residuals` methods for `"MoE_gating"` objects, i.e. `x$gating`.
  * Added `predict`, `fitted`, & `residuals` methods for `"MoE_expert"` objects, i.e. `x$expert`.
  * Minor edits to `predict.MoEClust` for models without expert network covariates.
  * Minor fixes to returned `x$gating` object for `equalPro=TRUE` models with a noise component.
* Various edits & documentation improvements to `MoE_gpairs`:  
  * Fixes to ellipses for models with expert covariates due to fix to `expert_covar` (see below).
  * `mosaic.pars` gains logical arg. `mfill=TRUE`, to toggle between filling select tiles with colour  
  (new default behaviour), or outlining select tiles with colour (old behaviour).
  * `boxplot.pars` arg. added to allow customising boxplot and violin plot panels,  
  with related fixes to colourisation in upper-triangular panels.
  * Fixes re: `scatter.pars$eci.col`: now governs colours of ellipses _and_ regression lines.
  * `scatter.pars$uncert.pch` added; now plotting symbols in covariate-related scatterplots  
  are only modified in `response.type="uncertainty"` plots when `uncert.cov` is `TRUE`.
  * Fixes to axis labels for diagonal panels involving factors.
  * Various colour-related args. now inherit sensible defaults if scatterplot colours are specified.
* `expert_covar` gains the arg. `weighted` to ensure cluster membership probabilities are properly  
  accounted for in estimating the extra variability due to the component means: defaults to `TRUE`,  
  but `weighted=FALSE` is provided as an option for recovering the old (not recommended) behaviour.
* A warning message is now printed if the MLR in the gating network ever fails to converge,  
  prompting the user to modify the `itmax` arg. to `MoE_control`: the 3<sup>rd</sup> element of this arg. governs  
  the maximum number of MLR iterations --- consequently, its default has been modified from `100` to  
  `1000` (thanks to a prompt from Dr. Georgios Karagiannis), which has the effect of slowing down  
  internal calls to `nnet::multinom` but generally reduces the required number of EM iterations. 
* Minor fix to `MoE_compare` whenever the optimal model needs to be refitted.
* Fixed conflict between `mclust::as.Mclust` & `MoEClust::as.Mclust`:  
`as.Mclust.MoEClust` now works regardless of order in which `mclust` & `MoEClust` are loaded.
* Stronger checks for variables in `gating` & `expert` formulas which are not found in `network.data`.
* Minor speed-up to initialisation for univariate response data with expert network covariates.
* Minor speed-ups to some other utility functions.
* Minor documentation, vignette, and vignette styling edits.

## MoEClust v1.3.3 - (_11<sup>th</sup> release [patch update]: 2020-12-29_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Minor `MoE_stepwise` speed-ups by avoiding duplication of initialisation for certain steps.
* Minor fix to `MoE_stepwise` for univariate data sets without covariates.
* Prettier axis labels for `MoE_uncertainty` plots.
* Minor CRAN compliance edits to the vignette.

## MoEClust v1.3.2 - (_10<sup>th</sup> release [patch update]: 2020-11-17_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* New `MoE_control` arg. `posidens=TRUE` ensures code no longer crashes when observations  
  have positive log-density: previous behaviour is recoverable by setting `posidens=FALSE`.
* `MoE_control` gains the arg. `asMclust` (`FALSE`, by default) which modifies the  
  `stopping` and  `hcUse` arguments such that `MoEClust` and `mclust` behave similarly  
  for models _with no covariates in either network_ (thanks to a request from Prof. Kamel Gana).
* Fixes to plotting colours & symbols in `MoE_gpairs` (thanks to Dr. Natasha De Manincor):  
  * Corrected mosaic panels (colours).
  * Accounted for empty clusters in all panels (colours & symbols).
* Fixed bug in `predict.MoEClust` when no `newdata` is supplied to models with no gating covariates.
* `MoE_clust` & `MoE_stepwise` now coerce `"character"` covariates to `"factor"` (for later plotting).
* Further improvements to `summary` method for `MoE_expert` objects.
* Fixes to `print` & `summary` methods for `MoE_gating` objects if `G=1` or `equalPro=TRUE`.
* Additional minor edits to `MoE_plotGate`.
* `print.MoECompare` gains the args. `maxi`, `posidens=TRUE`, & `rerank=FALSE`.
* Ensured `lattice(>=0.12)`, `matrixStats(>=0.53.1)`, & `mclust(>=5.4)` in `Imports:`.
* Ensured `clustMD(>=1.2.1)` and `geometry(>=0.4.0)` in `Suggests:`.
* Use of `NCOL`/`NROW` where appropriate.
* Package startup message now checks if newer version of package is available from CRAN.
* Updated citation info after publication in _Advances in Data Analysis and Classification_.
* Updated maintainer e-mail address.
* Minor documentation, examples, and CRAN compliance + `mclust` compatibility edits.

## MoEClust v1.3.1 - (_9<sup>th</sup> release [patch update]: 2020-05-12_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Maintenance release for compatibility with R 4.0.0 - minor edits.
* `summary.MoEClust` gains the printing-related arguments `classification=TRUE`,  
  `parameters=FALSE`, and `networks=FALSE` (thanks to a request from Prof. Kamel Gana).
* Related improvements to `print`/`summary` methods for `MoE_gating` & `MoE_expert` objects.
* Minor speed-up for `G=1` models with expert network covariates.
* Improvements to `MoE_plotGate`, with new `type`, `pch`, and `xlab` defaults.
* Added informative `dimnames` to returned `parameters` from `MoE_clust()`.
* Documentation, vignette, examples, and references improvements.

## MoEClust v1.3.0 - (_8<sup>th</sup> release [minor update]: 2020-03-30_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Various fixes and improvements to initialisation when there are expert network covariates:  
    * `MoE_mahala` now correctly uses the covariance of `resids` rather than the response.
    * New `MoE_mahala` arg. `identity` allow use of Euclidean distance instead:  
    this argument can also be passed via `exp.init$identity` to `MoE_control`.
    * Convergence of the initialisation procedure now explicitly monitored & sped-up.
    * Values of the criterion being minimised are now returned as an attribute.
    * The number of iterations of the initialisation algorithm are also returned as an attribute.
    * `MoE_control` arg. `exp.init$max.init` now defaults to `.Machine$integer.max`.
    * Improved checks on the `resids` arg. to `MoE_mahala`.
    * Greatly expanded the `MoE_mahala` examples.
* Improvements to `predict.MoEClust`:  
    * Now returns the predicted values of the gating and expert networks.
    * Now returns the predictions from the expert network of the most probable component  
    (`MAPy`), in addition to the (aggregated) predicted responses (`y`).
    * New arg. `MAPresids` governs whether residuals are computed against `MAPy` or `y`.
    * New arg. `use.y` (see documentation for details).
    * Now properly allows empty `newdata` for models with no covariates of any kind.
    * Fixed prediction for equal mixing proportion models when `discard.noise=FALSE`.
* Fixed small `MoE_stepwise` bugs when  
    * only one of `gating` or `expert` are supplied.
    * univariate response `data` are supplied.
    * moving from G=1 to G=2 with equal mixing proportions and no covariates.
    * discarding covariates present in the response data.
* Odds ratios now returned (and printed) when calling `summary` on `x$gating`.
* `noise_vol` now returns correction location for univariate data when `reciprocal=TRUE`.
* Spell-checking of documentation and fixes to `donttest` examples.

## MoEClust v1.2.4 - (_7<sup>th</sup> release [patch update]: 2019-12-11_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Fixed small bugs in `MoE_stepwise`:  
    * Improved checks on `network.data` and `data`.
    * Prevented `z.list` from being suppliable.  
    * Fixes when`equalPro="yes"` & `noise=TRUE`.
    * Fixes for supplying optional `MoE_control` arguments (also for `MoE_clust`).
    * Prevented termination if adding a component fails,  
    provided at least one other step doesn't fail.
* Fixed `discard.noise=TRUE` behaviour for `MoE_clust`, `predict.MoEClust`, &  
  `residuals.MoEClust` for models with a noise component fitted via `"CEM"`.
* Minor fixes to `noise_vol` function and handling of `noise.meth` arg. to `MoE_control`.
* Slight speed-up to E-step/C-step for models with a noise component.
* Initial allocation matrices now stored as attributes to `MoE_clust` output (see `?MoE_control`).
* Anti-aliasing of vignette images.
* Updated citation info after online publication in _Advances in Data Analysis and Classification_.

## MoEClust v1.2.3 - (_6<sup>th</sup> release [patch update]: 2019-07-29_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* Exported function `MoE_stepwise` for conducting a greedy forward stepwise  
  search to find the optimal model in terms of the number of components, GPCM  
  covariance parameterisation, and the subsets of gating/expert network covariates.
* `MoE_control` & `predict.MoEClust` gain the arg. `discard.noise`:  
  Default of `FALSE` retains old behaviour (see documentation for details).
* `MoE_control` gains the arg. `z.list` and the `init.z` arg. gets the option `"list"`:  
  this allows manually supplying (soft or hard) initial cluster allocation matrices.
* New args. and small fixes added to `MoE_gpairs`:  
    * `uncert.cov` arg. added to control uncertainty point-size in panels with covariates.
    * `density.pars` gains arg. `label.style`.
    * `scatter.pars` & `stripplot.pars` gain args. `noise.size` & `size.noise`.
    * `barcode.pars$bar.col` slightly fixed from previous update.
    * Colours for `"violin"` type plots now accurate for MAP panels.
* Slight speed-up to `noise_vol` when `method="ellipsoidhull"`.
* Small fix to `predict.MoEClust` when `resid=TRUE` for models with expert covariates.
* Small fix related to `...` construct for `residuals.MoEClust`.
* All printing related to noise-only models no longer shows the model name (there is none!).
* Other small fixes to `print.MoEClust`, `print.summary_MoEClust`, & `print.MoECompare`.
* Cosmetic fix to returned `gating` objects for `equalPro=TRUE` models. 
* Removed `parallel` package from `Suggests:`.

## MoEClust v1.2.2 - (_5<sup>th</sup> release [patch update]: 2019-05-15_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* `noise_vol` now also returns the location of the centre of mass of the region  
  used to estimate the hypervolume, regardless of the method employed. This fixes:    
    * `predict.MoEClust` for any models with a noise component (see below).
    * The summary of means for models with expert covariates and a noise component.
    * The location of the MVN ellipses for such models in `MoE_gpairs` (see below).
* Furthermore, calculation of the hypervolume in `noise_vol` for data with >2 dimensions  
  is now correct when `method="ellipsoidhull"`, owing to a bug in the `cluster` package.
* Other fixes and speed-ups for the `MoE_gpairs` plotting function:  
    * Added arg. `expert.covar` (& also to `as.Mclust` function).
    * Fixed location of MVN ellipses for models with noise & expert covariates (see above).
    * Fixes when `response.type="density"` for all models with a noise component.
    * Speed-up when `response.type="density"` for models with covariates of any kind.
    * Fixes to labelling for models with a noise component.
    * Fixed handling of `subset$data.ind` & `subset$cov.ind` arguments.
    * Barcode type plots now have colour for panels involving the MAP classification.
    * Barcode type plots now respect the arg. `buffer`.
    * Use of colour in `MoE_plotGate` is now consistent with `MoE_gpairs`.
* Fixes to how `gating` & `expert` formulas are handled:  
    * Allowed specification of formulas with dropped variables of the form `~.-a-b`.
    * Allowed formulas with no intercept of the form `~c-1`.
    * Allowed interaction effects, transformations and higher-order terms using `I()`.
    * Small related fixes to `drop_levels` & `drop_constants` functions.  
* `MoE_compare` gains arg. `noise.vol` for overriding the `noise.meth` arg.:  
  this allows specifying an improper uniform density directly via the (hyper)volume,  
  & hence adding noise to models for high-dimensional data for which `noise_vol()` fails.
* Fixed bug for `equalPro` models with noise component, and also added `equalNoise` arg.  
  to `MoE_control`, further controlling `equalPro` in the presence of a noise component.
* Fixes to `predict.MoEClust` for the following special cases:  
    * Fixes for any models with a noise component (see `noise_vol` comment above).
    * Accounted for predictions of single observations for models with a noise component.
    * Accounted for models with equal mixing proportions.
* Accounted for categorical covariates in the `x.axis` arg. to `MoE_plotGate`.
* `tau0` can now also be supplied as a vector in the presence of gating covariates.
* Fix to `expert_covar` for univariate models. 
* Slight `MoE_estep` speed-up due to removal of unnecessary `sweep()`.
* Small fixes for when `clustMD` is invoked, and added `snow` package to `Suggests:`.
* The `nnet` arg. `MaxNWts` now passable to gating network `multinom` call via `MoE_control`.
* Improved printing of output and handling of ties, especially for `MoE_compare`.
* Many documentation and vignette improvements.

## MoEClust v1.2.1 - (_4<sup>th</sup> release [patch update]: 2018-12-11_)
### New Features, Improvements, Bug Fixes, & Miscellaneous Edits
* New `MoE_control` arg. `algo` allows model fitting using the `"EM"` or `"CEM"` algorithm:  
    * Related new function `MoE_cstep` added.
    * Extra `algo` option `"cemEM"` allows running EM starting from convergence of CEM.
* Added `LOGLIK` to `MoE_clust` output, giving maximal log-likelihood values for all fitted models.
    * Behaves exactly as per `DF/ITERS`, etc., with associated printing/plotting functions.
    * Edited `MoE_compare`, `summary.MoEClust`, & `MoE_plotCrit` accordingly.
* New `MoE_control` arg. `nstarts` allows for multiple random starts when `init.z="random"`.
* New `MoE_control` arg. `tau0` provides another means of initialising the noise component.
* If `clustMD` is invoked for initialisation, models are now run more quickly in parallel.
* `MoE_plotGate` now allows a user-specified x-axis against which mixing proportions are plotted.
* Fixed bug in checking for strictly increasing log-likelihood estimates.

## MoEClust v1.2.0 - (_3<sup>rd</sup> release [minor update]: 2018-08-24_)
### New Features & Improvements
* New `predict.MoEClust` function added: predicts cluster membership probability,  
  MAP classification, and fitted response, using only new covariates or new covariates &  
  new response data, with noise components (and the `noise.gate` option) accounted for.
* New plotting function `MoE_Uncertainty` added (callable within `plot.MoEClust`):  
  visualises clustering uncertainty in the form of a barplot or an ordered profile plot,  
  allowing reference to be made to the true labels, or not, in both cases.
* Specifying `response.type="density"` to `MoE_gpairs` now works properly for models with  
  gating &/or expert network covariates. Previous approach which evaluated the density using  
  averaged gates &/or averaged means replaced by more computationally expensive but correct  
  approach, which evaluates MVN density for every observation individually and then averages.
* Added `clustMD` package to `Suggests:`. New `MoE_control` argument `exp.init$clustMD`  
  governs whether categorical/ordinal covariates are also incorporated into the initialisation  
  when `isTRUE(exp.init$joint)` & `clustMD` is loaded (defaults to `FALSE`, works with noise). 
* Added `drop.break` arg. to `MoE_control` for further control over the extra initialisation  
  step invoked in the presence of expert covariates (see Documentation for details).
* Sped-up `MoE_dens` for the `EEE` & `VVV` models by using already available Cholesky factors.
* Other new `MoE_control` arguments:  
    * `km.args` specifies `kstarts` & `kiters` when `init.z="kmeans"`.
    * Consolidated args. related to `init.z="hc"` & noise into `hc.args` & `noise.args`.
    * `hc.args` now also passed to call to `mclust` when `init.z="mclust"`.
    * `init.crit` (`"bic"`/`"icl"`) controls selection of optimal `mclust`/`clustMD`  
       model type to initialise with (if `init.z="mclust"` or `isTRUE(exp.init$clustMD)`);  
       relatedly, initialisation now sped-up when `init.z="mclust"`.

### Bug Fixes & Miscellaneous Edits
* `ITERS` replaces `iters` as the matrix of the number of EM iterations in `MoE_clust` output:  
    * `iters` now gives this number for the optimal model.  
	  * `ITERS` now behaves like `BIC`/`ICL` etc. in inheriting the `"MoECriterion"` class.  
	  * `iters` now filters down to `summary.MoEClust` and the associated printing function.  
	  * `ITERS` now filters down to `MoE_compare` and the associated printing function.
* Fixed point-size, transparency, & plotting symbols when `response.type="uncertainty"`  
  within `MoE_gpairs` to better conform to `mclust`: previously no transparency.
* `subset` arg. to `MoE_gpairs` now allows `data.ind=0` or `cov.ind=0`, allowing plotting of  
  response variables or plotting of the covariates to be suppressed entirely.
* Clarified MVN ellipses in `MoE_gpairs` plots.
* `sigs` arg. to `MoE_dens` & `MoE_estep` must now be a variance object, as per `variance`  
  in the  parameters list from `MoE_clust` & `mclust` output, the number of  clusters `G`,  
  variables `d` & `modelName` is inferred from this object: the arg. `modelName` was removed.
* `MoE_clust` no longer returns an error if `init.z="mclust"` when no gating/expert network  
   covariates are supplied; instead, `init.z="hc"` is used to better reproduce `mclust` output.
* `resid.data` now returned by `MoE_clust` as a list, to better conform to `MoE_dens`.
* Renamed functions `MoE_aitken` & `MoE_qclass` to `aitken` & `quant_clust`, respectively.
* Rows of `data` w/ missing values now dropped for gating/expert covariates too (`MoE_clust`).
* Logical covariates in gating/expert networks now coerced to factors.
* Fixed small bug calculating `linf` within `aitken` & the associated stopping criterion.
* Final `linf` estimate now returned for optimal model when `stopping="aitken"` & G > 1.
* Removed redundant extra M-step after convergence for models without expert covariates.
* Removed redundant & erroneous `resid` & `residuals` args. to `as.Mclust` & `MoE_gpairs`.
* `MoE_plotCrit`, `MoE_plotGate` & `MoE_plotLogLik` now invisibly return relevant quantities.
* Corrected degrees of freedom calculation for `G=0` models when `noise.init` is not supplied.
* Fixed `drop_levels` to handle alphanumeric variable names and ordinal variables.
* Fixed `MoE_compare` when a mix of models with and without a noise component are supplied.
* Fixed `MoE_compare` when optimal model has to be re-fit due to mismatched `criterion`.
* Fixed y-axis labelling of `MoE_Uncertainty` plots.
* `print.MoECompare` now has a `digits` arg. to control rounding of printed output.
* Better handling of tied model-selection criteria values in `MoE_clust` & `MoE_compare`.
* Interactions and higher-order terms are now accounted for within `drop_constants`.
* Replaced certain instances of `is.list(x)` with `inherits(x, "list")` for stricter checking.
* Added extra checks for invalid gating &/or expert covariates within `MoE_clust`.
* Added `mclust::clustCombi/clustCombiOptim` examples to `as.Mclust` documentation.
* Added extra precautions for empty clusters: during initialisation & during EM.
* Added utility function `MoE_news` for accessing this `NEWS` file.
* Added message if optimum `G` is at either end of the range considered.
* Tidied indentation/line-breaks for `cat`/`message`/`warning` calls for printing clarity.
* Added line-breaks to `usage` sections of multi-argument functions.
* Corrected `MoEClust-package` help file (formerly just `MoEClust`).
* Many documentation clarifications.

## MoEClust v1.1.0 - (_2<sup>nd</sup> release [minor update]: 2018-02-06_)
### New Features & Improvements
* `MoE_control` gains the `noise.gate` argument (defaults to `TRUE`): when `FALSE`,  
  the noise component's mixing proportion isn't influenced by gating network covariates.
* `x$parameters$mean` is now reported as the posterior mean of the fitted values when  
  there are expert network covariates: when there are no expert covariates, the posterior  
  mean of the response is reported, as before. This effects the centres of the MVN ellipses  
  in response vs. response panels of `MoE_gpairs` plots when there are expert covariates.
* New function `expert_covar` used to account for variability in the means, in the presence  
  of expert covariates, in order to modify shape & size of MVN ellipses in visualisations.
* `MoE_control` gains the `hcUse` argument (defaults to `"VARS"` as per old `mclust` versions).
* `MoE_mahala` gains the `squared` argument + speedup/matrix-inversion improvements.
* Speed-ups, incl. functions from `matrixStats` (on which `MoEClust` already depended).
* The `MoE_gpairs` argument `addEllipses` gains the option `"both"`.

### Bug Fixes & Miscellaneous Edits
* Fixed bug when `equalPro=TRUE` in the presence of a noise component when there are  
  no gating covariates:  now only the mixing proportions of the non-noise components  
  are constrained to be equal, after accounting for the noise component.
* `MoE_gpairs` argument `scatter.type` gains the options `lm2` & `ci2` for further control  
  over gating covariates. Fixed related bug whereby `lm` & `ci` type plots were being  
  erroneously produced for panels involving pairs of continuous covariates only.
* Fixed bugs in `MoE_mahala` and in expert network estimation with a noise component.
* `G=0` models w/ noise component only can now be fitted without having to supply `noise.init`.
* `MoE_compare` now correctly prints noise information for sub-optimal models.
* Slight edit to criterion used when `stopping="relative"`: now conforms to `mclust`.
* Added `check.margin=FALSE` to calls to `sweep()`.
* Added `call.=FALSE` to all `stop()` messages.
* Removed dependency on the `grid` library.
* Many documentation clarifications.

## MoEClust v1.0.0 - (_1<sup>st</sup> release: 2017-11-28_)
