Organic: update artwork, add harmonic knobs to control harmonic of each ...

...oscillator

Backwards compatibility is maintained by defaulting the oscillators to their old static values

The new logo was made by Umcaruje, I modified it a bit (mainly just adjusted hue to fit new artwork better)

Also, I improved the waveform knob's (and the new harmonic knob's) usability by adding plaintext descriptions to their knobhints, so the user will know what each setting means

- Addition:

The detuning scale was incorrectly calculated: instead of measuring in cents as it claims to, it was actually
in 1/100th octaves, so I fixed it so that I set the units to actual cents (1/100 seminote). Then I set the
range to +/-1200 cents and added compat code so that old values get multiplied by 12, to maintain backwards compat.