Add powertrip.py script

Has checks for missing __init__.py files in test directories.
Add execute permissions validator
Add Cython-generated C code validator
Complete refactoring of the code

Much cleaner and less duplication. Added docstrings and comments.
Add powertrip.py to Travis, manifest, changelog
Add __pycache__ directory to ignored dirs

Didn't know that py3 created these
Use sets instead of tuples

Thanks for suggesting this @ElDeveloper!
Merge pull request #453 from ElBrogrammer/issue-446

Added power-tripping tool