pyrsvg now part of python-gnome-desktop

The Python bindings for librsvg I started are now part of python-gnome-desktop. Robert Staudinger had submitted a bug report to GNOME's Bugzilla for librsvg support in python-gnome-desktop. He also included a patch with the basic infrastructure. I contributed the API changes I had made. Gustavo Carneiro reviewed them and proposed a few changes. The bindings will be part of the next stable branch of python-gnome-desktop.