matplotlib Code

Got steps_demo.py working

Got legend working with new transforms

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.

More code using new transformation framework. Lots of dead code
removed from backend_agg.cpp/h

Transferring work-in-progress

Bugfix and doc fixes in type1font.py

Sends paths to backend only once, and after that uses the "native" path by
reference with a changing transform. Started recongfiguring
patches.py to use only Paths under the hood (to take advantage of this
caching). Removed many methods from backend_agg that should
eventually be replaced by draw_path, at least in theory.

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...

Deleting this file to rename affine.py

Committing this file so I can rename it