matplotlib Code

Ability to use new, traited configuration system in mpl

Major refactor to separate out backend-specific stuff from
fontset-specific stuff. What used to be the Fonts class heirarchy is
now both a Fonts heirarchy and MathtextBackend heirarchy. This should
be further improved in the future when the backends themselves are
refactored to be more consistent.

Now uses the multi-sized delimiters in the BaKoMa fonts. This
prevents the square root symbol from getting overly wide as it gets
tall. (As auto-sized parens, brackets and braces etc.)

Removed last vestiges of old pcolor, scatter, quiver versions.

cleaner fill implementation

changed pcolor default to shading='flat'; related cleanups

Small optimization.

Add energy display in the same units as the potential

Add Schrodinger equation example, contributed by James Nagel <nagel@...>

tweaked cbook.dedent, inspired by Fernando's version

added config module, for testing a traited config system