switch from hslogger to purpose-built Utility.Debug

This uses a DebugSelector, rather than debug levels, which will allow
for a later option like --debug-from=Process to only
see debuging about running processes.

The module name that contains the thing being debugged is used as the
DebugSelector (in most cases; does not need to be a hard and fast rule).
Debug calls were changed to add that. hslogger did not display
that first parameter to debugM, but the DebugSelector does get
displayed.

Also fastDebug will allow doing debugging in places that are used in
tight loops, with the DebugSelector coming from the Annex Reader
essentially for free. Not done yet.

Command/SendKey.hs

@@ -5,6 +5,8 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
+{-# LANGUAGE OverloadedStrings #-}
+
 module Command.SendKey where
 
 import Command
@@ -14,8 +16,7 @@ import Utility.Rsync
 import Annex.Transfer
 import qualified CmdLine.GitAnnexShell.Fields as Fields
 import Utility.Metered
-
-import System.Log.Logger
+import Utility.Debug
 
 cmd :: Command
 cmd = noCommit $ 
@@ -45,14 +46,14 @@ start (_, key) = do
 
 fieldTransfer :: Direction -> Key -> (MeterUpdate -> Annex Bool) -> CommandStart
 fieldTransfer direction key a = do
-	liftIO $ debugM "fieldTransfer" "transfer start"
+	liftIO $ debug "Command.SendKey" "transfer start"
 	afile <- AssociatedFile . (fmap toRawFilePath)
 		<$> Fields.getField Fields.associatedFile
 	ok <- maybe (a $ const noop)
 		-- Using noRetry here because we're the sender.
 		(\u -> runner (Transfer direction (toUUID u) (fromKey id key)) afile Nothing noRetry a)
 		=<< Fields.getField Fields.remoteUUID
-	liftIO $ debugM "fieldTransfer" "transfer done"
+	liftIO $ debug "Command.SendKey" "transfer done"
 	liftIO $ exitBool ok
   where
 	{- Allow the key to be sent to the remote even if there seems to be