matplotlib Code

Get wxagg extension working again. Factor out the new Bbox conversion
code into agg_py_transforms.h

Increased coverage of backend_driver.py to include almost everything
in axes.py. Lots of little bug fixes.

Initial pass of Gtk, Qt, Qt4, Fltk and Wx GUI backends. Lots more
examples passing.

Removed transforms on the C++ side -- removed many methods that depend
on it in backend_agg in preparation for path generalization.
Lots of general renaming...

Creating branch to work on transforms/projections refactoring.