convert TopFilePath to use RawFilePath

Adds a dependency on filepath-bytestring, an as yet unreleased fork of
filepath that operates on RawFilePath.

Git.Repo also changed to use RawFilePath for the path to the repo.

This does eliminate some RawFilePath -> FilePath -> RawFilePath
conversions. And filepath-bytestring's </> is probably faster.
But I don't expect a major performance improvement from this.
This is mostly groundwork for making Annex.Location use RawFilePath,
which will allow for a conversion-free pipleline.

Command/Map.hs

@@ -176,7 +176,8 @@ absRepo reference r
 	| Git.repoIsUrl reference = return $ Git.Construct.localToUrl reference r
 	| Git.repoIsUrl r = return r
 	| otherwise = liftIO $ do
-		r' <- Git.Construct.fromAbsPath =<< absPath (Git.repoPath r)
+		r' <- Git.Construct.fromAbsPath
+			=<< absPath (fromRawFilePath (Git.repoPath r))
 		r'' <- safely $ flip Annex.eval Annex.gitRepo =<< Annex.new r'
 		return (fromMaybe r' r'')
 
@@ -234,7 +235,7 @@ tryScan r
 	  where
 		remotecmd = "sh -c " ++ shellEscape
 			(cddir ++ " && " ++ "git config --null --list")
-		dir = Git.repoPath r
+		dir = fromRawFilePath $ Git.repoPath r
 		cddir
 			| "/~" `isPrefixOf` dir =
 				let (userhome, reldir) = span (/= '/') (drop 1 dir)