Allow files to be removed from batch queues by number

This fixes issue #328.

The user actually *can* remove files from the batch queues in v3.19b, but you have to type the filenames which is not obvious from the prompt which implies you need to type the file index position (e.g. '1' for the first file in the queue). In all Synchronet versions prior, you could only remove by number (and not by name).

The fix is to allow either the number or the name of the file to be entered at the RemoveWhich prompt and the file is removed from the queue successfully.

Thanks Ragnarok!