Please implement a setting like filesystem.clean_names_callback, so that we can provide our own callback function for filtering names of files and directories.

The use case for this would be to let the users input file names like "Anställda" which will be automatically process to "anstallda".

Currently what is filtered is hard-coded in jquery.cleanname.js, and obviously one do not want to go around patching the source code of an included library/product like TinyMCE and its plugins.

As it is now, one can pretty much just disallow A-Z and give the user an error message. It would be smoother to just turn A-Z into a-z.