Auto generated UI

Major changes
- Allow different parameter types, but keep same syntax for "default" type
- Auto-generated UI sliders/buttons where requested by `SynthDemoDef`
- When returning parameters from synth, maintain order in which they were created
- Rename `synthesisBlock_` to `outputFrames_` for better understanding

Demos with auto-UI
- FM Synth
- Basic Delay
- Compressor Demo (non-ducking)