Use ES6 Import

[rubas]

As mentioned in brianzinn/react-babylonjs#110 .

[brianzinn]

thanks rubas really appreciate you making this PR - Will put out an NPM after updating rollup.

[brianzinn]

hi @rubas I have made some additional changes for rollup - the imports changed to ie: @babylonjs/core/scene and were not being resolved as external, so the package was 1.5 MB (instead of 47kB!) and I was seeing duplicates in the treemap as well. You can try with yarn add [email protected]. In a CRA project what I noticed was no difference on the build size - are you able to verify against the beta version that I published? I see the client.html treemap is 7.94MB (stat) --> 3.44MB (parsed) --> 803kB (gzip) according to the analyzer, but I'm getting that with new and original versions (I didn't read up on next-transpile-modules). I'm hoping to get everything sorted out here before trying to fix react-babylonjs. I'm trying to find the 2MB difference that you reported on the react-babylonis issue, so hoping you can show me where that is. Thanks for your help 😃