Matrix4.lookAt(): y doesn't need to be normalized because it's a cross product of 2 normalized vectors

Not sure it's really correct, it's kinda hard to tell.

Also made stress test more fancy and heavy. It's interesting how antialiasing increases performance difference for more complex materials.

Also some shaders refactoring.

Still todo: doubleSided handling for reflections / refractions.

As per discussion in #1324

This fixes geometry tessellation example (before TextGeometry by default was having UVs defined for just a subset of faces).

Fixed: The DOMRenderer was not using the correct members from the result of the projectScene() function, which ended up meaning that no DOM elements were being updated at all.

Also trying to make a bit nicer UVs for ExtrudeGeometry / TextGeometry.

Is as it was before, but I implemented the event dispatching in a different way (checking the distance of the object position between frames). Also renamed the 'update' event to 'change'.

controls.addEventListener( 'change', render );

Right now only misc_camera_trackball.html uses this.

At least till we don't have this solved somehow better I think we should keep the old one. New one makes everything using it feeling broken, it's distracting.

Moved new event-driven `TrackballControls` into `TrackballControlsExperimental`. For the moment used just in "misc_camera_trackball.html" example.

Fixed example. For some reason the clearColor was killing the shadows (and antialias, something to do with alpha I guess).

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.