Changed camera matrix update in WebGLRenderer to happen just once per frame, no need to do it with every object.

Premultiplied alpha in WebGLRenderer for MeshColorFillMaterial and MeshColorStrokeMaterial (to get closer to CanvasRenderer look).

Refactored multimaterials to also work with non-textured models composed from multiple material groups.

Old version was doing massive overdraw (whole mesh was drawn for each material).

Even current solution is still quite messy: there is a different behavior for stroke and fill materials (when used as secondary materials).

Stroke materials are applied to the complete mesh (as most common use case seems to be wireframe) while fill materials now apply only to faces within single material group (when "decalIndex" property of secondary fill material is set).

Changed WebGLRenderer to use 3x3 normal matrix.

Limitations of WebGL lights:

- currently handles only single one of each ambient/directional/point light
- light intensity modifier not yet taken into account
- only diffuse term (this applies also in CanvasRenderer)

Added multipass multimaterials to WebGLRenderer.

Refactored WebGLRenderer shader to become proto-mini-ubershader (untershader :).

Line width is currently not set properly on Chrome in Windows:

http://code.google.com/p/chromium/issues/detail?id=60124

Added OBJ converter test example.

Modified Three.js to handle converted models:

 - extended WebGL renderer to use texturing
   - broke down model into multiple VBOs according to materials
   - textures are lazy created when images get loaded
     (converter takes care of resizing images to nearest power of 2
      dimensions using 2d canvas)

 - changed material array semantics in Mesh object
    - before: multiple materials were applied to all faces (broken in WebGL, needs multitexturing shader)
    - now: there is only single material per face, but one mesh can have faces with different materials

 - added per vertex normals (to get smooth shading in WebGL)

* `CanvasRenderer` and `SVGRenderer` basic lighting support (`*ColorStroke`/`*ColorFill` only)
* `Renderer` > `Projector`. `CanvasRenderer`, `SVGRenderer` and `DOMRenderer` do not extend anymore
* Interactivity base code (hdi folder). To be refactored... ([mindlapse](http://github.com/mindlapse))
* Added `computeCentroids` method to `Geometry`
* Included `Stats.js` directly in the `/examples` folder to avoid the need of internet for playing around

 * Bug Fix: Matrix4.makeInvert was calling a non existent scale method. Replaced with multiplyScalar.
 * Bug Fix: DirectionalLight wasn't normalizing the direction vector.
 * Added lights to the scene for test.html

 * Add lighting code in the scene rendering loop

 * Added float precision in shader code to shaders compile now.
 * Changed occurrences of WebGL typed Arrays and UnsignedShort typed arrays to new array types

* `Face4` now supports `MeshBitmapUVMappingMaterial`
* Changed order of `*StrokeMaterial` parameters. Now it's `color`, `opacity`, `lineWidth`.
* `BitmapUVMappingMaterial` > `MeshBitmapUVMappingMaterial`
* `ColorFillMaterial` > `MeshColorFillMaterial`
* `ColorStrokeMaterial` > `MeshColorStrokeMaterial`
* `FaceColorFillMaterial` > `MeshFaceColorFillMaterial`
* `FaceColorStrokeMaterial` > `MeshFaceColorStrokeMaterial`
* `ColorStrokeMaterial` > `LineColorMaterial`
* `Rectangle.instersects` returned false with rectangles with 0px witdh or height

- Matrix4.lookAt fix (CanvasRenderer and SVGRenderer now handle the -Y)
- Color class now using 0-1 floats instead of 0-255 integers