This transform replaces all wires with nodes in a legal, flow-forward
order

Move pad to object ConstantPropagation so other transforms can use it

* add graph node classes

* add graph representation usage pass

* remove pass using graph nodes so that firrtl can compile

* move google graph ir nodes to altIR package

Also let Travis know that equivalence checks can take a while

Add Yosys formal equivalence checking to Travis regressions

Also add Travis test for running this script on PRs

Defined as the range from ' ' to '~' [0x20, 0x7e]

This prevents collisions for one prefix (including temp) from
incrementing the suffix for other prefixes. Makes names more stable.

Refactor StringLit to use String instead of Array[Byte]

When calling verilator in a subdirectory like ./test_run_dir/...
verilator will read the verilog file from the current working directory
if there is a file there with the right name.  This fix specifies
the specific path of the verilog file intended.

not exit when --help is included in program flags

Adds programArgs to commonOptions
programArgs is all arguments on command line with out leading -/+
or are not bound to a flag.
Create simple test

* Update sbt to 0.13.16; add Scala 2.12 support.
To clean, test, and build Scala 2.11 and Scala 2.12 versions:
  % sbt +clean +test +publishLocal

* Update Travis to test in 2.11.11 and 2.12.3

* Try different way of providing Travis Scala version

* Attempt to get verilator built before tests.

* Make pathsInDAG walk all possible paths

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

* Use linearization order when finding all paths in DAG

Since InstanceGraph now has all modules in its graph, test ConstProp on all modules as a default behaviour.

- Need to think about how to target ConstProp only for a specific module?

Close #644

* Added option to emit final annotations

* Removed extra > from output-anno-file

* Removed other extra > from input-anno-file

* Reorder port and wire assignments in Verilog

* Fixed up syntax

bug fix for cases when we want to flatten a module in which a module is instantiated multiple times (#634)

* initial implementation of InlineDeepTransformation

* rewrote transformation to not have any side effects in terms on inlining that was not annotated to be inlined

* minor rewrites

* renamed transformations to Flatten

* fixes according to review

* added more comments and fixed formating/style

* fixed spacing, minor style fixes

Fix ConstProp bug where multiple names would swap with one