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.

Assistant/TransferQueue.hs

@@ -92,7 +92,7 @@ queueTransfersMatching matching reason schedule k f direction
 			filterM (wantSend True (Just k) f . Remote.uuid) $
 				filter (\r -> not (inset s r || Remote.readonly r)) rs
 	  where
-	  	locs = S.fromList <$> Remote.keyLocations k
+		locs = S.fromList <$> Remote.keyLocations k
 		inset s r = S.member (Remote.uuid r) s
 	gentransfer r = Transfer
 		{ transferDirection = direction