PEP8 style guidelines

[nirum]

I think we ought to keep in line with the PEP8 style guidelines.

Commits 4149aff, 1a4444b, ff5a1c8 and b709dca fix most of these issues.

I had to make some breaking changes in order to do this, mostly with the names of some functions and some optional arguments. Before, we were using camelCase, now everything (I think) uses underscore_case.

speaking of which, we should have a changelog