get, move, copy, mirror: Added --failed switch which retries failed copies/moves

Note that get --from foo --failed will get things that a previous get --from bar
tried and failed to get, etc. I considered making --failed only retry
transfers from the same remote, but it was easier, and seems more useful,
to not have the same remote requirement.

Noisy due to some refactoring into Types/

Command/MetaData.hs

@@ -40,7 +40,7 @@ optParser :: CmdParamsDesc -> Parser MetaDataOptions
 optParser desc = MetaDataOptions
 	<$> cmdParams desc
 	<*> ((Get <$> getopt) <|> (Set <$> some modopts) <|> pure GetAll)
-	<*> optional (parseKeyOptions False)
+	<*> optional parseKeyOptions
 	<*> parseBatchOption
   where
 	getopt = option (eitherReader mkMetaField)