matplotlib Code

Optimize shared axes (to prevent calling set_xlim/set_ylim more than
once per axes per update).
Save figure at correct dpi.
General cleanup and optimizations.

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...

New milestone -- resizing figure window works. shared_axis_demo.py
works. (Uses callbacks to track changes between axes's).

Milestone -- simple_plot.py working with new affine framework (with
the exception of dpi propagation)

Second pass, using a stateful transform tree.

Just marking a milestone -- about to totally rip things up again.

Running mathtext_demo.py without transforms.py/cpp. Totally broken,
though. Not surprising... ;)

Baby steps and horrible breakage on transforms branch.

Creating branch to work on transforms/projections refactoring.