Confirm NPM package works as intended

[swift502]

Need to check if https://www.npmjs.com/package/sketchbook is a usable package.

• Update NPM package to current commit
• A custom glb scene must be easy to load with the package
• Asset paths must be relative to the npm package folder, so they don't break
• Check that embedded Type definitions work as intended, and the NPM package offers autocompletion
• Return NPM usage section to the readme