[v3] Concurrent playback, nested collections, loops and more.

[slurmulon]

Summary

This is the largest release for bach to date. It's basically a complete rewrite that adds support for:

• Completely new bach.json format (via bach.compose/compose) with quantized step states, enabling 100% stateless and linear iteration.
• Nestable lists, sets and loops
• Concurrent beat element playback
• Duration aliases (e.g. bar, beat, 4n, 16n, etc.)
• Unique and deterministic beat element ids
• Play and stop events for beat elements
• ... basically, most/all of the major limitations with bach v2 have been addressed

Issues

• :microscope: ClojureScript test suite (via npm test) is currently broken due to node's Crypto and our polyfill.
  • Using the polyfill fixes tests but breaks the UMD builds in consumer libraries such as bach-js and gig.
• :factory: ESM and UMD builds are temporarily disabled due to ongoing complications with crypto polyfill.

Future

• :shipit: Publish latest version to NPM and Clojars
• :construction: Allow bach.compose/compose to accept a domain configuration object, which can provide:
  • Reserved variables (good for music, as we can represent all note pitches as variables like :c0, :f2s, :e5b, etc.)
  • Custom step unit (right now the greatest common duration is used, which is perfect for music but not for other domains such as animations).
  • etc.
• :construction: Post-compose tempo modification
• :microscope: Tests for bach.data, bach.tree and bach.math namespaces.
• :microscope: More integration tests
• :factory: Revisit shadow-cljs build to properly support ESM and UMD bundles (currently using ./index.js shim for ES6+ imports)
• :fire: Use slingshot library for improved error handling and reporting.
• :recycle: Use defrecord and such for Element, Beat, etc.