legend frame and font size.

I just sent patches about this to matplotlib-devel. The

    > current version has two problems with this:

Until these are incorporated, there is still an easy way to customize
the legend text (and other properties of legends) which is illustrated
in http://matplotlib.sf.net/examples/legend_demo.py. Here is the
approach, in brief

    leg = legend(... legend args here)
    texts = leg.get_texts()
    set(texts, fontsize='small', color='r')