Revert "Switch to mainline pyverilog"

This reverts commit 5d3125f.

This commit adds back requirements.txt so we can point to our forked
version of pyverilog.

.travis.yml

@@ -30,7 +30,8 @@ install:
 
 - pip install twine
 - pip install python-coveralls
-- pip install pytest-cov pytest-codestyle
+- pip install pytest-cov pytest-codestyle fault
+- pip install --ignore-installed -r requirements.txt
 - pip install -e .
 after_success:
 - coveralls

README.md

@@ -117,6 +117,7 @@ $ cd magma
 
 Install magma as a symbolic package
 ```
+$ pip install -r requirements.txt
 $ pip install -e .
 ```
 

requirements.txt

@@ -0,0 +1 @@
+-e git+git://github.com/leonardt/Pyverilog.git@add-nd-arrays#egg=pyverilog

setup.py

@@ -28,7 +28,7 @@
         "astor",
         "six",
         "mako",
-        "pyverilog",
+        # "pyverilog",
         "numpy",
         "graphviz",
         "coreir>=2.0.*",