Working with ES6 classes, iterable properties and other 'modern JavaScript' stuff

[sole]

People want to use 'modern JavaScript' with tween.js but some things just don't quite work as you would expect. Sometimes it is due to the way we iterate before deciding which properties to tween, other times it's a consequence of how classes are not 'exactly' objects so things are not iterable. Other times it might be a consequence of transpilers rewriting code so what you see isn't exactly what tween.js sees.

The end result is that things do not work as you expect them to work, which isn't good.

(some) related issues:
tweenjs/tween.js#287
tweenjs/tween.js#267

[dalisoft]

@sole please look at here and here. i hope you like it

[trusktr]

We've got modern syntax now, and it is also now TypeScript. I think we can close this discussion, and open any new one based on the latest code.