fix some mixed space+tab indentation

This fixes all instances of " \t" in the code base. Most common case
seems to be after a "where" line; probably vim copied the two space layout
of that line.

Done as a background task while listening to episode 2 of the Type Theory
podcast.

Command/Copy.hs

@@ -23,7 +23,7 @@ seek ps = do
 	to <- getOptionField toOption Remote.byNameWithUUID
 	from <- getOptionField fromOption Remote.byNameWithUUID
 	withKeyOptions
-	 	(Command.Move.startKey to from False)
+		(Command.Move.startKey to from False)
 		(withFilesInGit $ whenAnnexed $ start to from)
 		ps