parallelization

[Rudxain]

Right now, the main thread isn't the bottleneck, it's the API. But when users are allowed to set droplet speed, we'll need WebWorkers.

I'll have to benchmark before doing so, as the context API calls may be I/O bound rather than CPU-bound. Especially considering that droplets are rendered by repeatedly drawing individual chars, rather than drawing batches of chars

[Rudxain]

If I RIIR before this, I should remember that std::thread can only be emulated by wasm_thread, so WebWorkers are the only stable way

[Rudxain]

I expect that WebGL auto-distributes workload across GPU cores, so there's no need for WebWorkers to handle slices of the Canvas, as that would require multiple API calls (counterproductive)