Also fixed RTT example - seems UV mapping for SphereGeometry is now rotated 180 degrees.

Too much caching can break things.

Now uses Face4 where posible.
Adde phiStart, phiLenght, thetaStart and thetaLength as extra parameters (useful for doing google-earth-like stuff).

And still readable code...

It's enough to clone just for hits, no need to do it for every face.

Removed some clone() calls while still keeping the code somewhat pretty.

So we can set it to lowp for mobile devices if needed.

Actually, this would break cameras added as childs of objects, reverting.
So there is no clear and simple way to handling multiple scenes unfortunatelly.
Encouraging `scene.add( camera )` seems like the right thing to do then, less problems.

Actually, I think this can be handled magically instead of requiring understanding of the concept that the camera is part of the scenegraph.
While I was at it, I fixed it so you can use a camera for rendering different scenes (the renderer will add it and remove from each scene graph)	.

Removed LOD text example. I think LOD example is good enough.
Ubiquity test working again.
Tweaked README to show the new pattern (Scene first thing created).

Code is a horrible mess but at least it works. Anyways, some day we should revisit GPU accelerated skinning with a proper pipeline.

I had to resurrect parts of old code (keeping track of scene graph changes).

Good news: performance is great, new scene graph gains compound with buffers optimizations and non-array materials refactoring. Together we gained about 15% for rotating cubes performance test (pushing max to 2650 cubes at 60 fps).

Still broken with new scene graph: lod, skinning, collisions, AnaglyphWebGLRenderer, ParallaxBarrierWebGLRenderer, multi-canvas circle example.

Also moved `.overdraw` to Material.
Code is much simpler now :)

Noticeable difference: can't anymore assign Material references to faces directly - "face.materials" became "face.materialIndex". Materials have to go to "geometry.materials" array (to which "face.materialIndex" points). This is necessary to allow run-time changing of face materials (this indirection used to be done by arrays).

Some casualties:

- multi-materials example, this functionality isn't possible anymore
- had to simplify LOD Text examples as LODs don't handle groups (used to fake multi-materials)
- multi-materials sphere in materials example can't have faces with undefined materials (this may be fixable I guess, when there'll be some real use-case)
- scene format still has materials arrays, only the last material will be used (except when there are face materials, then materials from JSON will be used, as before)

Other renderers and their corresponding examples were not touched yet.

WebGLRenderer still needs some prettification, some things don't make sense anymore without arrays, code can be cleaned up further.

Lots of code got cleaner with seconds, seems we used them before all around.

Also changed examples that didn't need deltas to simple Date.now() plus some more examples cleaning, trying to get rid of obsolescence warnings.

Do not merge, this is very experimental, not sure about correctness, also tons of unsolved things.

Before lighting was messed up in dynamically generated cube maps.

Dynamic cube maps need to have flip uniforms (flipEnvMap / tFlip) set to 1, static cube maps to -1 (default).

For standard materials this is handled automatically, it's just something to be aware of when using cube maps in custom ShaderMaterials (dynamic and static cube maps have different cube face orientations, dynamic ones are correct, static ones need flipped x-axis in lookup vector).

There is still mystery of disappearing last cube face (negative-Z) and weirdly clipped objects in cars demo (works ok in simpler test).

Now `Camera` can use inherited `update()`

Turns out I had it right before after all: to get rid of artefacts it should be multiplied by diffuse term (instead of being patched by conditional).