Note that NetworkX works with Python 3.3
Merge remote-tracking branch 'upstream/master'
Add pydot fix from issue #923

Patch from http://www.geofrogger.net/review/0001-Dot-files-with-grouped-edges-are-not-treated-properl.patch
Merge pull request #930 from hagberg/pydot-fix

Pydot fix.
Fixes #932