use lock pools throughout git-annex

The one exception is in Utility.Daemon. As long as a process only
daemonizes once, which seems reasonable, and as long as it avoids calling
checkDaemon once it's already running as a daemon, the fcntl locking
gotchas won't be a problem there.

Annex.LockFile has it's own separate lock pool layer, which has been
renamed to LockCache. This is a persistent cache of locks that persist
until closed.

This is not quite done; lockContent stil needs to be converted.

Annex.hs

@@ -57,7 +57,7 @@ import Types.Messages
 import Types.UUID
 import Types.FileMatcher
 import Types.NumCopies
-import Types.LockPool
+import Types.LockCache
 import Types.MetaData
 import Types.DesktopNotify
 import Types.CleanupActions
@@ -120,7 +120,7 @@ data AnnexState = AnnexState
 	, trustmap :: Maybe TrustMap
 	, groupmap :: Maybe GroupMap
 	, ciphers :: M.Map StorableCipher Cipher
-	, lockpool :: LockPool
+	, lockcache :: LockCache
 	, flags :: M.Map String Bool
 	, fields :: M.Map String String
 	, modmeta :: [ModMeta]
@@ -166,7 +166,7 @@ newState c r = AnnexState
 	, trustmap = Nothing
 	, groupmap = Nothing
 	, ciphers = M.empty
-	, lockpool = M.empty
+	, lockcache = M.empty
 	, flags = M.empty
 	, fields = M.empty
 	, modmeta = []