Cleanup

Some cleanups.

- Removed executable bits
- Changed module names to under_scores
- Renamed `blockID` module to `blocks`. I think `from blocks import WOOD` is the most natural way to import a wooden block. An alternative would be `block_ids`. What do you think?
- PEP8 cleanup
Yeah. It's within the letter of LICENSE.txt, but I think it's part of the spirit of open source to give credit where possible.