matplotlib Code

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

Add a background color to the axes so it's easier to tell if there is
a bug in the masked values.

Small bugfix to compile on gcc 4.x (Thanks, Eric)

update enthought package to version 2.6b1, stripped of setuptools
installed in site-packages, if not already present

move configobj.py to lib/, install in site-packages only if required

First pass at Cairo support on the branch.

Update to use modern Numpy C API

Further speed improvements. Quadmesh extension code (still not as
fast as the old version, for various reasons.)
Fix bugs in quadmesh masking in PDF and PS backends.

update Copyright

add Shapely as a Requirement.