Fix display of unicode filenames.

Internally, the filenames are stored as un-decoded unicode.
I tried decoding them, but then haskell tries to access the wrong files.
Hmm.

So, I've unhappily chosen option "B", which is to decode filenames before
they are displayed.

Backend/WORM.hs

@@ -67,5 +67,5 @@ checkKeySize key = do
 				then return True
 				else do
 					dest <- moveBad key
-					warning $ "Bad file size; moved to "++dest
+					warning $ "Bad file size; moved to " ++ showFile dest
 					return False