Side-by-side diff view in Github

Adds the option to view diffs side-by-side in Github

This extension will transform the diff view on Github to a side-by-side view. Just load a commit page and click the "Show Side-By-Side Diffs" button. Things that work: - Switch between side-by-side and unified diffs - Previous comments are shown - New comments can be added to any line, but they look funky until you reload. Found a bug? Have a feature you'd like but isn't working? Please contribute at http://github.com/smike/diffhub.