Require invalidate in compatibility code. Implicitly invalidate all
wires so that explicit invalidate is only required for IOs

Disambiguate DontCare reference in initializeSingletons() avoiding compilation error during unidoc generation.

Use DontCare on `outs` not `ins` in InvalidateAPISpec.
Add additional InvalidateAPISpec tests demonstrating selective override of Strict/NotStrict behavior.

* Require explicit connection to DontCare to generate "is invalid".

* Add tests for RefNotInitializedException.
Currently, we fail the when ... otherwise ...

* Disable ScalaTest shrinking on error in ComplexAssignSpec.

* fix broken merge; still some binding issues

* cleanup DontCare connection checks; add missing directions to test module IOs

* Have library code inherit compileOptions from the enclosing Module (if it exists).

* work around current firrtl uninitialized references with Strict compile options and explicitInvalidate

* more CompileOptions cleanup; move test-specific defines to package object

* minimize differences with master

* set default CompileOptions.explicitInvalidate to false until we fix the FIRRTL when issue

* ignore the StrictCompiler property checks (until  CompileOptions.explicitInvalidate is defaulted to true)

* Revert "more CompileOptions cleanup; move test-specific defines to package object"

This reverts commit e4486edcba990d150e76e08a2fc6abca033556e0.

* Revert "work around current firrtl uninitialized references with Strict compile options and explicitInvalidate"

This reverts commit 426faa430a62c3dac2dbdf33044d3386d4243157.

* remove unused code

* Convert to binding-based DontCare implementation

* comment cleanup to minimize differences with master

* Tentatively remove possibly redundant DefInvalid on module ports.

* Respond to code review change request.
- backout build.sbt change
- correct indentation
- handle bulk of DontCare semantics in elemConnect()
- have DontCare extend Element, not Data (eliminate most Object specific methods
- add comments indicating reason for explicit DontCare connections

* Initialize test elements without requiring a DontCare.

* Respond to review change requests.
- DontCare should work on left or right side in BiDirectional connections
- call bind() to set DontCare binding instead of messing with internal variables
- DontCares are only equivalent with DontCares
- clean up processWhens() definition

* Eliminate DontCare connection to inputs in MonoConnect().

* Pull aggregates apart for the purpose of DontCare connections.

* Restore the explicit (conditionally executed) ports DefInvalidin ImplicitModule()

* Don't add DontCare's to the module list of _ids.

* Add missing DefInvalid() to LegacyModule().

* Respond to review requests: add DontCare BiConnect Vec, remove null parent hack to avoid addId(), initialize singletons early in Builder

* Move DontCare out of chisel3.experimental.

Addresses #419

cloneType is now marked (through comments only) as an internal API.
chiselCloneType deprecated (and changed to cloneTypeFull internally, analogous to cloneTypeWidth).
chiselTypeOf(data) introduced as the external API to get a chisel type from a hardware object
Intended usage: cloning is an implementation detail, and chisel types and hardware objects both should act as immutable types, with operations like Input(...), Reg(...), etc returning a copy and leaving the original unchanged. Hence, the clone operations are all deprecated.
Deletes what appears to be an unused Bundle companion object.
Input(...), Output(...), Flipped(...) require the object to be unbound

* Generate aggregate coverage but publish a single Jar

* Reduce the aggressive dis-aggregation as it breaks super project aggregation.

To clean, test, and build Scala 2.11 and Scala 2.12 versions:
  % sbt +clean +test +publishLocal

* Added API to get Verilog from Chisel

* Removed second emitVerilog implementation, added scaladoc

Incorporated suggestions from @edwardcwang

Preprocess chisel3 IR before emission to determing whether
whens have alternatives.

Rest of the binding refactor

Bool implements Reset. Compatibility package includes an implicit
conversion from Reset to Bool.

For a start from a plain Ubuntu you need Java first before sbt

or sbt-scoverage is updated to deal with dependencies.
Unfortunately, enabling this revives the publishing of the coreMacros and chiselFrontend jars and we don't want that.

No functional changes

* Fix style of literal creators
Literal creators for UInt, SInt and Bool were declared with parens, but
virtually all uses of these methods do not use parens.  This is for
issue #539.
This fix is an API breaking change. If anyone has used parens, e.g.
val x = 1.U()
This will now be an error

* remove trailing parens from literal creators in IntegerMathTester