Support for verilog memory loading. (#840)

* Ability to load memories at simulation startup
* first pass
* create annotation
* create skeleton Transform

* Work in progress
Building out transform and pass now

* Support for LoadMemory annotation
* Creates chisel and firrtl LoadMemory annotations
* LoadMemoryTransform converts annotation into BlackBox InLine
* Simple test that verilog bound modules get created.

* Support for LoadMemory annotation
* Supports Bundled/multi-field memories
* more tests
* support for `$readmemh` and `$readmemb`
* warns if suffix used in file specification.

* Support for LoadMemory annotation
* Use standard chisel annotation idiom

* Support for LoadMemory annotation
* Fixes for @seldridge nits and super-nits

* Support for LoadMemory annotation
- transform now only runs if emitter is an instance of VerilogEmitter
- suffixes on memory text files are now respected
  - if suffix exists and memory is aggregate, aggregate sub-fields will now be inserted before suffix
- every bind module created gets a unique number
  - this is required when multiple loaded memories appear in a module
  - this should be generalized for other uses of binding modules

* Support for LoadMemory annotation
- remove un-needed suffix test

* Support for LoadMemory annotation
- remove instance walk, now just processes each module

* Support for LoadMemory annotation
- Move LoadMemoryTransformation into Firrtl for treadle to access it.

* Support for LoadMemory annotation
- One more bug in suffix handling has been eliminated

* Support for LoadMemory annotation
- remove unused findModule per jackkoenig
- fixed complex test, bad filename edge case

* Support for LoadMemory annotation
- changed to not use intellij style column alignment for : declarations

* Load memory from file
Fixes based on @jkoenig review
- remove unused BindPrefixFactory
- Moved code from CreateBindableMemoryLoaders into to LoadMemoryTransfrom
- Made map to find relevant memory annotations faster
- Made map to find modules referenced by annotations faster
- Made things private that should be private
- DefAnnotatedMemorys are no longer referenced, shouldn't be found here.
- println of error changed to failed

* Loading memories from files
- Many changes based on review
- move stuff into experimental
- clean up annotation manipulation
- manage tests better
- use more standard practices for transform

* Loading memories from files
- More review changes
- Move doc from annotation to the object apply method that generates the annotation
- Make scalastyle directives more specific
- Use more efficient collect to generate name to module map
- Made lines obey style length limit
- a couple of cleanups of imports in tests
- removed some commented out code
- optimized checking for lines using .exists
- use _ for unused variable in match

(cherry picked from commit a5185d2c)