optimise

03cb2c8ece put a cat-file into the fast
bloomfilter generation path. Instead, add another bloom filter which diffs
from the work tree to the index.

Also, pull the sha of the changed object out of the diffs, and cat that
object directly, rather than indirecting through the filename.

Finally, removed some hacks that are unncessary thanks to the worktree to
index diff.

Git/DiffTree.hs

@@ -12,6 +12,7 @@ module Git.DiffTree (
 	diffTreeRecursive,
 	diffIndex,
 	diffWorkTree,
+	diffFiles,
 	diffLog,
 ) where
 
@@ -66,6 +67,10 @@ diffIndex' ref params repo =
 		, return ([], return True)
 		)
 
+{- Diff between the index and work tree. -}
+diffFiles :: [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
+diffFiles = getdiff (Param "diff-files")
+
 {- Runs git log in --raw mode to get the changes that were made in
  - a particular commit. The output format is adjusted to be the same
  - as diff-tree --raw._-}