matplotlib Code

Add first attempt at getting matplotlib to install mathtex.

Update the mathtex branch so that it is up-to-date with trunk.

Try to add merge tracking to the mathtex branch.

Add support for mathtext.default to the OS X backend. This still requires testing from a Mac user.

Speed up quiver for large numbers of arrows; key tip given by Ray Speth.

Update the INSTALL file so that it includes information about mathtex.

added Tony's radar chart demo

axes_zoom_effect.py modified to use floats (instead of strings) for alpha values

Fix an error importing afm.py.

Simplify plot argument handling code.
The only side effect of the change should be that previously,
plotting multiple columns required that x and y have the same
number of columns, or that one of them have only one column.
Now the plotting simply cycles through the columns of both,
wrapping back to the first column as needed.