Dogebox2 and Midbox FM Operator Additions

[Mid-The-Modder]

Porting over Dogebox2's ability to use custom FM frequencies, add a Hz offset, and invert the operator wave. Of course, in typical Midbox fashion; with some more additions on top.

• Unisons on individual FM operators?
• Setting the phase of the individual FM waves. This would work by directly taking the waveform from an operator waveform and shifting it by an interval given by an offset/phase slider, likely with 64 values each offsetting the waveform by Config.sineWaveLength / 64 samples each.
• Some sort of option to remove operator chorus offsets and volume balancing, likely in an advanced settings system. (Advanced Instrument/Song Settings #92)