Reduce bundle size

[robertlong]

Spoke is currently very large. The project page vendor bundle is 3.2mb. There are a number of heavy modules in the Spoke code base right now that can either be removed, rewritten, or tree-shaken.

Candidates for removal:

• HLS.js: if we can get video thumbnails for live streams or just use a static image, that should be good enough.
• SketchfabZipLoader: If we have a backend service that proxied Sketchfab glTF zip requests and returned a glb instead then we could get rid of this module and speed up project load times immensely.
• Recast: if we can get rid of nav-mesh generation then we can get rid of Recast. This seems unlikely to happen soon.

Candidates for rewriting:

• react-color: This package includes react-css which includes all of lodash. We're only using one of the pickers (Sketch Picker) and we can probably rewrite this to use styled-components instead.

Candidates for tree-shaking:

• three.js: Work is already underway to make this happen. I'm tracking Add sideEffects: false flag to package.json to allow tree shaking mrdoob/three.js#16059 and will implement it when possible.