`Commit#diff` should just forward to `Tree#diff`.
`Commit#diff` should just forward to `Tree#diff`.

saraid/rugged,tpickett66/rugged,Acidburn0zzz/rugged,Acidburn0zzz/rugged,libgit2/rugged,Acidburn0zzz/rugged,saraid/rugged,libgit2/rugged,libgit2/rugged,tpickett66/rugged,tpickett66/rugged,saraid/rugged