matplotlib Code

Add an empty matplotlibrc to the tests/ directory so that running the test suite uses the default matplotlib config.

add script to consolidate difference images

save difference image between failed image and baseline image

Updated 'fill' to handle unitized data. Added a unit-test for it.

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.

Unit-Test harness initial check-in.