Automate tests for cythonized *.c files

[whart222]

It's recommended that Python packages leveraging Cython embed their associated *.c files. We need to find a way to test that these files are up-to-date w.r.t. changes in their associated *.py files.

[mrmundt]

In an effort to clean up old issues, we are moving some design discussions to our Archived Design Discussions wiki.