BLI_filename_make_safe had several issues:
* Would replace all dots ('.'), not a great idea since it would break extensions.
* Was not checking for 'control' ASCII chars (though unlikely, better to be safe here).
* Win32 only: was not checking for forbidden names (con, aux, ltp0, com0, etc.).
New BLI_path_make_safe() simply checks each path's item with BLI_filename_make_safe().
d7b9202567