Updating for compatibility with three@>=0.80.0

[foorjdev]

This PR moves toward compatibility with react@>=0.80.0, though some issues still remain. The main problem I'm running into is that for some reason prop type validation fails whenever THREE entities are passed as props (e.g. passing a THREE.Vector3 for position). Despite spending a fair amount of time trying to follow the exact sequence of function calls involved in prop validation, I'm still unable to locate the source of the failure.

If I understand correctly, THREE entities are validated by looking at the name of the constructor (for example, if we have var v = new THREE.Vector3(), then v.constructor.name === 'Vector3'). But this appears to be entirely consistent with three@>=0.80.0, leading to very strange validation error messages like Failed prop type: Invalid prop 'position' of type 'Vector3' supplied to 'perspectiveCamera', expected instance of 'Vector3'.

Finally, I've added an implementation of THREE.HemisphereLight, though no tests have been written for it yet.

[toxicFork]

Awesome, thanks! I will take a look to see how we can resolve the issues you mentioned :)

[toxicFork]

Woo, solved the issues! Let's see what travis says and we can merge to master :D

Also will need to update the examples... Doing that now :)

Thanks for the help @foorjdev !!! ❤️