Release Candidate Firmware V1.21 RC4

[ianski]

Finally got round to givng the new fireware a spin. Everything seems to be working great.
Love the new OSC's and the artifacting at high pitches is cool too
I never realized it was possible to cross moduate using the LFO AMP slots, that is genuis!
The OS is really maturing nicely, looking forward to seeing other features being wrapped up.
This thing is going to be a monster with the expander(s).