use ByteStrings when reading annex symlinks and pointers

Now there's a ByteString used all the way from disk to Key.

The main complication in this conversion was the use of fromInternalGitPath
in several places to munge things on Windows. The things that used that
were changed to parse the ByteString using either path separator.

Also some code that had read from files to a String lazily was changed
to read a minimal strict ByteString.

Command/Smudge.hs

@@ -22,7 +22,8 @@ import qualified Git
 import qualified Git.Ref
 import Backend
 
-import qualified Data.ByteString.Lazy as B
+import qualified Data.ByteString as S
+import qualified Data.ByteString.Lazy as L
 
 cmd :: Command
 cmd = noCommit $ noMessages $
@@ -62,14 +63,14 @@ seek UpdateOption = commandAction update
 --   smudge filter in memory, which is a problem with large files.
 smudge :: FilePath -> CommandStart
 smudge file = do
-	b <- liftIO $ B.hGetContents stdin
-	case parseLinkOrPointer b of
+	b <- liftIO $ L.hGetContents stdin
+	case parseLinkTargetOrPointerLazy b of
 		Nothing -> noop
 		Just k -> do
 			topfile <- inRepo (toTopFilePath file)
 			Database.Keys.addAssociatedFile k topfile
 			void $ smudgeLog k topfile
-	liftIO $ B.putStr b
+	liftIO $ L.putStr b
 	stop
 
 -- Clean filter is fed file content on stdin, decides if a file
@@ -77,13 +78,13 @@ smudge file = do
 -- injested content if so. Otherwise, the original content.
 clean :: FilePath -> CommandStart
 clean file = do
-	b <- liftIO $ B.hGetContents stdin
+	b <- liftIO $ L.hGetContents stdin
 	ifM fileoutsiderepo
-		( liftIO $ B.hPut stdout b
-		, case parseLinkOrPointer b of
+		( liftIO $ L.hPut stdout b
+		, case parseLinkTargetOrPointerLazy b of
 			Just k -> do
 				getMoveRaceRecovery k file
-				liftIO $ B.hPut stdout b
+				liftIO $ L.hPut stdout b
 			Nothing -> go b =<< catKeyFile file
 		)
 	stop
@@ -97,7 +98,7 @@ clean file = do
 			-- to free memory when sending the file, so the
 			-- less we let it send, the less memory it will waste.)
 			if Git.BuildVersion.older "2.5"
-				then B.length b `seq` return ()
+				then L.length b `seq` return ()
 				else liftIO $ hClose stdin
 
 			-- Optimization for the case when the file is already
@@ -108,7 +109,7 @@ clean file = do
 					( liftIO $ emitPointer ko
 					, doingest oldkey
 					)
-		, liftIO $ B.hPut stdout b
+		, liftIO $ L.hPut stdout b
 		)
 	
 	doingest oldkey = do
@@ -158,7 +159,7 @@ shouldAnnex file moldkey = do
 		Nothing -> isNothing <$> catObjectMetaData (Git.Ref.fileRef file)
 
 emitPointer :: Key -> IO ()
-emitPointer = putStr . formatPointer
+emitPointer = S.putStr . formatPointer
 
 -- Recover from a previous race between eg git mv and git-annex get.
 -- That could result in the file remaining a pointer file, while