[GSoC] GSoC python variant final update

[Lenna Peterson]

Post: http://arklenna.tumblr.com/post/29808300789/

The coordinate mapper, with updated documentation, is now located on
this branch: https://github.com/lennax/biopython/tree/f_loc4
It awaits the merging of Peter's f_loc4 branch.

I've written an entry on coordinate mapping for the Cookbook:
http://biopython.org/wiki/Coordinate_mapping

Additionally, at Peter's suggestion, I've written a clarification of
strand as it relates to transcription and translation. It's available
here: https://docs.google.com/document/d/11R7EOJXn90lN5_SmaPOyN5rFfPQybbCbUBo6EY0R0pA/edit

It's been a great experience working with this project this summer.
Thank you to everyone involved.

Cheers,

Lenna