0.5

• Bring space complexity down to D^2 (Bodigrim).
• Add Bifunctor instance (Jonathan King). Requires base >= 4.8.
• Fix for the grouped context diff. It was omitting all trailing contexts.
• Allow unlimited number of context elements (getContextDiffNew).

0.4

• Generalize Diff a to PolyDiff a b. Diff has been replaced with a specialized synonym type Diff a = PolyDiff a a, but it's still not backward compatible if you imported Diff(..).