matplotlib Code

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.

Change default joinstyle to round

Rework the nan-handling/clipping/quantizing/simplification
framework so each is an independent part of a pipeline.
Expose the C++-implementation of all of this so it can be
used from all Python backends. Add rcParam
"path.simplify_threshold" to control the threshold of
similarity below which vertices will be removed.

Fix path simplification by a) making it more conservative about when it will simplify based on segment length, and b) honoring path.simplify rcParam in Agg backend.

Merge branch 'mathdefault'

Start eliminating obsolete and temporary rcParams key, numerix.npyma module

[ 2316591 ] assertion is always true

Fix some python2.6 -3 warnings. (mainly usage of has_key)

[ 2089958 ] Path simplification for vector output backends

added backend_fallback to traited config