Add separate Issue and PR templates

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

Recursive literal lookup needs to be guarded against combinational loops
Added a test-case to illustrate the issue when CheckResets is run before CheckCombLoops

Supply a trait to allow user annotations to provide JsonProtocol type hints

* Closes #1162
* Instances of extmodules remain in the final hierarchy
* Extmodule definitions are not renamed or duplicated
* The rest of the pass may proceed as normal

* Fixes #1154
* Tests that #1154 example produces SyntaxErrorsException
* Generally helps catch trailing syntax errors
* Performance-neutral relative to previous grammar
* Recommended by antlr4 devs, can help performance in some cases
* See antlr/antlr4#1540

Guard initial blocks in emitted Verilog with `ifndef SYNTHESIS

Change findInstancesInHierarchy to return implicit top instance

Co-Authored-By: Jack Koenig <koenig@sifive.com>

* Change FIRRTL-internal API, affecting only one corner case
* Make API more "DWIM" and consistent with other methods
* Add test cases for findInstancesInHierarchy
* Update Scaladoc

Enhance CheckCombLoops errors with connection info

* Closes #1203

* Add Scaladoc for EdgeData API

* Include stringified vertices in EdgeNotFoundException

Emit Verilog else-if for Register Updates

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

Modifies the Verilog emitter to emit "else if" blocks as opposed to
more deeply nested "else begin if" blocks. This improves the output
Verilog readability.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

Fix handling of read enables for write-first (default) memories in VerilogMemDelays

* Additional refactoring to clean up pass implementation

* Make register names match old scheme to appease CI

Major features:

- Added Interval type, as well as PrimOps asInterval, clip, wrap, and sqz.
- Changed PrimOp names: bpset -> setp, bpshl -> incp, bpshr -> decp
- Refactored width/bound inferencer into a separate constraint solver
- Added transforms to infer, trim, and remove interval bounds
- Tests for said features

Plan to be released with 1.3

Make TopWiringTransform Idempotent

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

This changes TopWiringTransform to remove TopWiringAnnotations after
it runs.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

* Replace instance analysis code with InstanceGraph API calls

* Add convenience implicits for using TargetTokens as safe boxed strings