fix minor typo
Teach slicer how to act like a tremolo:

* add amp_min and amp_max to limit/stretch the range of the slicer
Add new noise synths:

* white noise - noise
* brown noise - bnoise
* pink noise  - pnoise

Each noise synth also has a rlpf attached to it for joy and giggles.

synth :bnoise, amp: 0.2, cutoff: 80, res: 0.1