TODO:

  - maybe image array loader should go into TextureCube.js so that people could just reuse the code

  - it may be worth to be able to specify different combination of environment map and underlying material (in single render pass),
    currently color/color map/environment map are multiplied, though addition also produces very interesting looking materials

GouraudShading and PhongShading ⟶ SmoothShading

This is actually tricky due to multimaterials and vertex normals.

The practical effects of "shading" parameter in WebGLRenderer are currently following:

- if your model has vertex normals, now you can "dumb down" its shading by specifying THREE.FlatShading for MeshLambertMaterial and MeshPhongMaterial
- if your model has only face normals, it will always have just flat shading, no matter which shading you set, no escape from this
- if your model has multiple materials, smooth shading always "wins", meaning if there is at least one smooth shaded material in multimaterial group, all other materials in this group will be also smooth shaded (this is solvable by having multiple normal buffers, but seems wasteful, at least for the moment, till there are no practical use cases)

Currently implemented shading / material combinations:

  - MeshNormalMaterial: FlatShading [default], GouradShading
  - MeshDepthMaterial:  no shading parameter in material, uses own specific shading
  - MeshBasicMaterial: no shading parameter in material, uses own specific shading
  - MeshLambertMaterial: FlatShading, GouraudShading [default]
  - MeshPhongMaterial: FlatShading, PhongShading [default]

Not all features from the new material format are implemented yet, though already now it's more powerful than the old format (you can now use  texture also in Basic and Phong materials).

Also started to retire old model format: removed old OBJ converter and meshes that it generated.

TODO:
 - take into account shading and blending parameters
 - transplant cube map support from experimental material

Almost done porting CanvasRenderer to the new material system (plus some performance gains on the way :D)
`Color` now handles hex with no alpha byte (probably there is a nicer way of doing it...)

Experimenting with different syntax for materials (just hex instead of THREE.Color in API), checking how it feels with shaders example.

First attempt at MeshBasicMaterial / MeshLambertMaterial / MeshPhongMaterial. Also: testing branching :)

This is not supposed to work yet, all is in the flux, do not base any code on this.

In Chrome it looks more or less ok, but it has some problem in Firefox 4 (with some camera angles there are black areas around edges).

Also updated Python builder scripts and examples to include this new material.