matplotlib Code

Numpification new try: dont touch numerix/, but make mpl code independent of it.
(Including conversion to "import numpy as npy")
Complete except for pylab.py and mlab.py

reverted numerix breakage, with apologies

completed numpification of most trivial cases

finished numpification of extension code and axes.py

efficient support for new Yahoo format in finance.py

Fixed date format bug in finance.py that was crashing finance_demo.py

some more units refactoring

added mikes units patch

applied isnan to numarray and other misc

fixed a key is None bug