PEP8 + comments

Hi,

I was trying to package the last version (0.7.3) and I came up with bugs with python3 which are fixed in master already.
* 0.7.3 is not on pypi.
* is it possible to release 0.7.4 to have a working version with python3?

Since I started a branch before I figured out what was going on, I fixed some PEP8 mistakes.

Best.
Francois.