mute group access

I miss a way to check via Lua for the mute group of a given note and instrument. This will be essential when bringing my “Split into separate tracks” tool to 3.0.

Sure thing. There are a few other “new” properties missing as well:
one_shot, overlapping_mode (keyzones), map_velocity_to_volume and map_key_to_pitch.

Will all add them in the next beta to complete the Lua API fundamentals for r3.