Towards 1.0

[wbinnssmith]

I'd like to start tracking progress towards rebound.js 1.0. All it will be is the solidification of what has already been the accepted API for rebound for the past few years. At the same time, we can take the opportunity to clean up a few minor imperfections, make its core even smaller, and launch a shiny new website.

• activateSpring -> activateSpringById (#24)
• Split out utils as a separate entry point (can be import utils from 'rebound/utils') so that those who just need the core of rebound don't pull in extra bytes.
• Establish browser support as the same as React's, meaning:
  • Require ES5 (no need to implement Function.prototype.bind and others internally) but support environments with it shimmed (such as IE9+)
  • Browsers haven't prefixed requestAnimationFrame in 5+ years
• Docusaurus Website

Please let me know about any concerns, and if you feel something else should be a part of 1.0. We'll likely have a couple of prerelease versions before we publish.

In the meantime I'd like to launch rebound.js v0.1.0, which will simply be building and distributing rebound after its moderate refactoring, flowification, and new build infrastructure with rollup flat bundles. Keep an eye out for that soon.

cc @willbailey, @appsforartists, @JoelMarcey

[appsforartists]

We replaced Rebound with Wobble, so I am probably not going to be very helpful in testing. Glad to see this maintained again though!

[JoelMarcey]

@wbinnssmith Definitely willing to help with the site creation via Docusaurus.