Python Google Chart

Support for QR code chart types and several
missing chart features were added. Several bugs
were fixed, including charts being downloaded
twice, pie charts not being generated correctly,
and "None" values causing errors.

Automatic chart scaling, support for Sparklines, Radar, Google-o-Meter, and Map chart types, and other changes and bugfixes.

The download_chart() call was renamed to
download(). The Axis code was refactored to allow
for multiple axis labels. A set_axis_labels() bug
with non escaped characters was fixed.