Changes for the latest ahkab

Hi!

I merged in most of the changes in your ahkab fork. Very nice work. I had to do it offline because there were a few things I wanted to keep out, at the same time you'll be duly credited in the changelog.

I have added a few bugfixes and a few easy things I had in the back of my mind and I wanted to do since some time (including full PEP8 compliance, which should make it nicer to hack).

I have modified `toyga` to take into account the changes in the latest `ahkab`, here in this pull request are the changes.

Everything should work out of the box if you install the latest `ahkab`, just locally to your user with the `--local` flag is enough.

It was very interesting to see this genetic algorithm in action!

All the best,

GV