Espruino plugin for Rollup module bundler

Actually I just tried import * as name from "module-name"; and it does tree-shaking there based on the usage of the module too - so hopefully require would still allow tree-shaking (just maybe not in all cases).

I think realistically 90% of users will still use require because that's what all the existing Espruino docs use/suggest, so it'd be good if it could be made to work. Seems a shame if after all the work of adding rollup, most people never actually saw the benefits.

But yeah, this all looks really promising, With terser as well this could be a really good system.