Calling SceneUtils.cloneObject fails when adding an
Object3D with compiled JS file as THREE.MarchingCubes
hasn't been defined.

As per discussion in #1889.

That took a while... but I think it makes sense...

Tried to make it as straight foward as possible. Kept the extrac base url thingie :)
Thinking of moving BinaryLoader to examples/js/loaders.... what do you think @alteredq?

Using xhr.addEventListener instead of xhr.onreadystatechange. Changed 'complete' event to 'load' as native JavaScript.

JSONLoader next...

The only confusing part of this approach is the event object that gets dispatched. For ImageLoader you need to look for event.image, and for OBJLoader you need to look for event.object. Maybe it should be consistent for all and just be event.content?

Hesitant on whether this should extend Loader or not. I guess we'll see whether is needed or not once we have more features.

Fixes #1866

Fixes #1866

Also added rudimentary position-based vertex colors to MarchingCubes object and example for testing.

There is no normalization or anything, it's up to application layer not to set colors beyond <0,1> range.

This addresses issue #1834

removing less necessary stuff from Path.js. May still have to decide whether to migrate to using .curves from .actions