Implement scheduler #9
Description
Summary
Add a scheduler to the app, and a way for expressions to plug into it.
Why
- There are scant sequencers not requiring a clock.
- MIDI delay/echo is cool.
- This could be nice for throttling/rate-limiting CCs... or not overwhelming a poor old TX81Z's MIDI buffer.
Considerations
- Here be dragons - at some point in every norns app's life, a clock (or 10) is added. And at some point soon after, that clock starts exhibiting inconsistencies.
- It seems that most folks have the best luck with monolithic clocks. From there, you can use ticks. Or you can use arbitrary delays, compensate for timing inconsistencies, and probably make a big mess. Whatever makes sense.
- This may require some work in code seemingly unrelated to, but affected by, the relentless onward march of the clock. It's pretty likely that there will be "rabbit holes" in computationally intensive processes where limits need to be placed, states need to be persisted, and things need to be resumed at a more opportune time.
- Scheduled tasks are basically threads. This introduces new problems to figure out: identifying, stopping, resuming, managing environments per-thread.