Add (optional) anti-alias filter

[transcriptaze]

Ref. https://community.vcvrack.com/t/sn-beta-testing-help/21198/13?u=transcriptaze

sn-vco

• [x] None
• [x] 1x oversampling, 12.5kHz LPF
• [x] 1x oversampling, 2x 16kHz LPF
• [x] 2x oversampling, 16kHz LPF
• [x] 2x oversampling, 2x 16kHz LPF
• [x] 4x oversampling, 16 kHz LPF
• [x] 4x oversampling, 2x 16 kHz LPF
• [ ] Indicator LED
• [x] Configure on context menu

sn-vcox

• [ ] Configure from sn-vco
• [ ] 1x oversampling, 12.5kHz LPF
• [ ] 1x oversampling, 2x 16kHz LPF
• [ ] 2x oversampling, 16kHz LPF
• [ ] 2x oversampling, 2x 16kHz LPF
• [ ] 4x oversampling, 16 kHz LPF
• [ ] 4x oversampling, 2x 16 kHz LPF
• [ ] Indicator LED

Misc

• [ ] ALIASING.md

[twystd]

• squinkylabs: More on aliasing
• Alias-Free Digital Synthesis of Classic Analog Waveforms
• Is there such a thing as band-limited non-linear distortion?
• Benefit of Anti-Aliasing for Wideband Finite Time Duration Signals prior to Sampling
• Digital Anti Aliasing Filter For Waveform Band Limiting
• Does MSAA make sense in audio / 1d data streams?
• Can we have a Digital Anti Aliasing filter?
• Are oversampling and downsampling the same thing?
• Bleps via State Machine