Add Python GTK+ 3 Tutorial
It would be great if the Python GTK+ 3 Tutorial could be added to Damned Lies.
Since the whole tutorial is created using Sphinx, I followed the steps suggested on the mailing list. The PO(T) files are located at https://github.com/sebp/PyGObject-Tutorial/tree/master/translations
Please let me know if there's anything else you need.