matplotlib Code

Change missing header file errors into warnings, since include paths
can be inserted in sneaky ways behind distutils' back ;)

Minor speed improvements from profiling. Fix kerning corruption issue when
"shrinking" characters.

Reverting last change since it breaks on gcc-4.2

Attempting to reduce compiler warnings for gcc-4.2 (which I don't
have, but Darren Dale has reported some new warnings).

Small bugfix with auto-sized delimiters

Add support for \widehat and \widetilde

Improved exception handling. Remove compiler warning.

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

Minor mathtext bugfixes

Convert _ttconv.cpp to use raw Python/C API, rather than CXX.