Loading custom songs with useMidiForCues set to True

[Alternity156]

NotReaper should read the midi file for these songs, using a translated version of the midi2cues.py script included in the game files.

[aggrogahu]

This is a pretty niche situation, though should be addressed. Although NR is mostly for anyone new to mapping, anyone moving from Reaper to NR will run into this issue.

Also, the best course of action seems to be, in loading songs with useMidiForCues set to True, the editor should convert all existing difficulties from midi to cues, and then disable useMidiForCues, with all future changes being saved to cues.

Only concern is if a user for some reason wants to go back and forth between cues editing in NR and midi editing in Reaper (perhaps someone is used to editing in Reaper, and only wants to try NR for a little bit). Perhaps a confirmation message should be displayed notifying the user that the map is being converted to use cues? That way users will get a heads up before converting and disabling useMidiForCues, and then they can figure out on their own the best way to proceed.