Due an a conflict between one of the libraries used by Firediff and just about everything else, I have pushed the Firediff release schedule forward some and rolled a 0.2.1 release.
This release includes fixes for the extension conflict, a new text diffing algorithm that will hopefully give better results as well as provide the basis of the unified diff feature that is planned for 0.1, and a few minor bug fixes to the Snapshot UI.
Thank you to all of those who notified me of this conflict.