Enable tabs on the project file.
PBGitLane can be used from multiple threads. This means using a static variable isn't safe. Added a _laneIndex ivar to PBGitGrapher to prevent multiple instances of PBGitGrapher from interfering with each other.
Better handling of thread cancelation. Fixes pressing command-R rapidly in the history view and sometimes having no commits show.
Merge pull request #332 from ksuther/threading-fixes

Threading fixes for minor UI glitches