matplotlib Code

Added Karen Tracey's threading_test.py.

Removal of numerix, stage 2.
The only vestiges are a couple method names, and a validator
with a warning to catch numerix keys in matplotlibrc files.

Small fixes to test_pdf_use14corefonts.py, thanks to Nicolas Grilly

Commit Nicolas Grilly's use14corefonts patch

Fix an infinite recursion in the unit registry when trying to find a converter for a sequence of strings. Add a test for this to unit/nose_tests.py

added legend to markevery tests

added markevery property to Line2D

added nose tests

commented out seterr in npy -- ma looks broken here

Remove more obsolete files from unit subdirectory