lots of fixes to the previous untested release:
- no longer requires 2^N frames buffer
- record offset initialized more correctly (doesn't glitch at non-integer write speeds), and can't be modulated (it's more dangerous than useful.)
- silence output when play is disabled
- clamp rate to +/- 32 so it doesn't crash Max
- clamp SVF freq to 1/2 nyquist so it doesn't explode
- update filter with per-sample rate change
- fix filer modulation algo.