ptrac usage description and yet another author

3 things:

1. We're on a 4 page limit. 3 pages are full now. The PTRAC usage description is okay imho, but if we hit the limit we can throw it out without losing much meaning.
2. I've added myself as an author (issue pyne/ans-winter-2013#3). I thought the only way to make sense of the A and C superscripts was to fill myself into the "B place". Feel free to move me around as you like.
3. Regarding "The Cython interpreter". I think the terminology is false. It's a compiler. It eats cython code and produces C (or something like that). Or does it do any interpreting?