Fixes #1866

Fixes #1866

Maybe we need a build/custom/ThreeCore.js though...

As per discussion in ee946579

As per discussion here in ee946579

Anaglyph and ParallaxBarrier could also be merged somehow, as the only change is the fragment shader.

See discussion here: https://github.com/mrdoob/three.js/commit/6e002f324a06f6f766b50c930732a9994fdd4ac6#commitcomment-1234473

This is a typical blender asset usage approach.  Linked
content can be included in a new blend file but it cannot be edited in
the file that links it.

Upgraded the blender exporter to understand linked groups and add them
to an exported scene.

Added "webgl_loader_scenegroup_blender.html".  This example shows
blender linked groups to demonstrate changes made to the
blender exporter.  The table.blend links an object group (cup and
silverware) from the dinnerset.blend file.  This example does not
incorporate the location offsets in the group definition which it really
should.  Being a new threejs user I did not know how best to do it.

I tried to move BinaryLoader to /examples/js but SceneLoader needs it.
Curious to hear what people thinks about this change.

Some weird warning saying THREE.REVISION isn't defined :/
Need to improve this build.py some day...

This probably could be done in some nicer way, but at least there is no more direct dependency in WebGLRenderer (and lib shrunk ;).

- removed not anymore existing ro.me specific remains (triggers, mesh colliders and shadow volumes)
- added custom properties for setting shadow map casting and receiving, depthWrite, depthTest, blending, doubleSided
- using Blender native "transparency" checkbox for setting out "transparent" property
- better handling of messed up texture slots

This is required for SSAO. Unfortunately scene.overrideMaterial is not enough for proper depth pass. Like for shadow maps, shader animated objects (like morphs) need different depth materials than static objects.

Now we can do things like this:

controls = new THREE.TrackballControls( camera );
controls.addEventListener( 'update', render );

Sadly, some examples are slightly broken until we have better pipeline for assets load complete event dispatching.