matplotlib Code

cleaned up output of mathmpl and plot directive; added thumbnail gallery

more updates to docs

preparing to move entire web site to sphinx; things may be whacked for a day or so

Oops in last commit.

Rename mathpng to mathmpl

Workaround for broken search engine in Sphinx

Add initial support for inheritance diagrams.

use htmlonly directive to cleanup a few items in the pdf document:
link to pdf download
release, date and comment at beginning of each part which was poorly
formatted and somewhat redundant in the pdf document

Add plot directive to include inline plots and their source.

Fix latex doc build by removing some more obscure symbols that aren't
likely to be installed and adding "txfonts" to preamble.