made modulator match carrier better... found a very suspicious looking line
todo: figure out which of these lines is correct, in the morning.
I think that feedback should not be applied before the frequency multiplier, and everything sounds more accurate that way.
Increased amount of feedback.
This makes the "trumpet" and "guitar" instruments of VRC7 sound much better.
I couldn't do this before because feedback was applied in the wrong place so at high modulation rates it would distort with much less feedback, but that was fixed in previous commit.
Release 0.56