[API] If possible speed up Set MIDI actions for very big items

So the actions like MIDI_SetNote get a good velocity in many MIDI messages if they are scattered across many MIDI Items, but if the same quantity of MIDI messages are together in a big MIDI item the performance ramps down. Look at this code exemple that get all notes and just set it with the same value: Code:

sight... posted on the wrong sub sorry if anyone can move it :p

When lots of midi Sets, rather work at string level this requires only one API call. This is what unleashed juliansader midi scripts.