matplotlib Code

Removal of numerix, stage 2.
The only vestiges are a couple method names, and a validator
with a warning to catch numerix keys in matplotlibrc files.

Render all the fonts in each mathtext expression to a single image buffer
(memory and time savings).
Add support for getting raw image data for mathtext expressions.
Add mathtext_wx.py example showing how to put mathtext expressions
into controls.

remove trailing spaces

added some unit tests