matplotlib Code

added link to usetex wiki

minor docstring fixes

updated comments in matplotlibrc.template concerning font.size

added a dvipng hack to allow mac users to get nice results with usetex

these changes should have gone in with the last commit regarding font.size

removed warning about ps.useafm breaking mathtext from matpltolibrc.template

Dropped support of tex engine in usetex, to focus on latex

improved usetex to respect serif, sans-serif, monospace, and cursive rc settings

added delimiter to pylab save

matplotlibrc text.usetex now checks for dependencies during validation.
For usetex option, backend_ps does all the work in the os's temp directory.
matplotlibrc ps.usedistiller can now be set to None, ghostscript, or xpdf.
xpdf produces high quality output and small files, but needs testing.
Dependencies are checked during the validation process.