matplotlib Code

Remove the "markup" kwarg and rcParam everywhere and replace it with
an automatic detection of math markup.

Fix mathtext_demo to use markup="tex" kwarg.

Add kwarg 'markup' for all text that allows the user to choose either
'plain' or 'tex' markup. A default may also be provided in the
rcParam 'text.markup'.
Minor bugfix to mathtext.py

Merging mathtext changes into trunk.

remove trailing spaces

added pnpoly for better poly hit testing

mathtext performance enhancements

symc to 0.72

fixed mathtext color bug

added shadow effect