matplotlib Code

Got mixed text/math working for Agg, Ps (non-afm) and Pdf (non-afm).
All other backends can be considered horribly broken on this branch.

Standardized imports in ticker.py

Bugfix in changed import strategy

recleanup of axes imports

add some comments to new RcParams class

validate rcParams

ticker.py import numpy rather than numerix

Fix charOverChars (\angstrom)

Add support for bf (bold) and sf (sans serif) math fonts.

Add support for Latex2e-style math fonts (\mathrm, \mathit etc.)
Add support for function name shortcuts (\sin, \cos etc.)
Raise an exception when encountering double subscript or superscripts
(e.g. x_i_j)