use filepath-bytestring for annex object manipulations

git-annex find is now RawFilePath end to end, no string conversions.
So is git-annex get when it does not need to get anything.
So this is a major milestone on optimisation.

Benchmarks indicate around 30% speedup in both commands.

Probably many other performance improvements. All or nearly all places
where a file is statted use RawFilePath now.

Command/Multicast.hs

@@ -137,7 +137,8 @@ send ups fs = do
 				mk <- lookupFile f
 				case mk of
 					Nothing -> noop
-					Just k -> withObjectLoc k (addlist f)
+					Just k -> withObjectLoc k $
+						addlist f . fromRawFilePath
 			liftIO $ hClose h
 			
 			serverkey <- uftpKey