* THREE.Rectangle: `_x1`, ` _x2`, `_y1`, `_y2` ⟶ `_left`, `_right`, `_top`, `_bottom`

If you want to use binary format, convert OBJ models using "convert_obj_threejs_slim.py" with "-t binary" option.

This will now create two files:
    JS part with materials
    BIN part with binary buffers

Binary models are loaded like this:

loader.loadBinary( 'obj/lucy/Lucy250k_bin.js', function( geometry ) { createScene( geometry, s ) }, "obj/lucy" );

(difference to ascii format is that url root must be always specified so loader can find binary buffers file, like it already was for textures)

Good news:

- raw binary files are quite smaller than raw ascii files (about half size)
- loading times went down about 20-25%
- now also Firefox can handle 250k triangle mesh (it just bugs about long running script), with ascii format it threw "array initialiser too large" exception

Mixed news:

- gzipped binary files are only about 25% smaller than gzipped ascii files so actual benefits are smaller,
  also it's more likely server will have JS gzipping on by default, while you need to set it up for
  other formats (could be hacked around by naming binary files with JS extension instead of BIN?)

Bad news:

- browser blocking is back :( Not that it ever went completely away (for large models object creation is more costly than loading and it is blocking), but it was slightly better with ascii loader (where data is loaded as worker's JS body).

    - this comes from having to use Ajax to load binary data
    - loading binary data by Ajax from within worker didn't really help, it was in fact slightly slower and browser did freeze :(
    - can't easily embed binary data in JSON (would need to encode it which would make it bigger, defying the purpose)

- Loader got fatter

Also in this commit: renamed Loader.loadAsync() => Loader.loadAsciiOld() and Loader.loadWorker() = Loader.loadAscii() so that names correspond to model formats instead of underlying implementation.

loadAsciiOld - JS exported by Blender and old OBJ converter
loadAscii    - JSON created by slim OBJ converter (-t ascii)
loadBinary   - JSON + BIN created by slim OBJ converter (-t binary)

TODO:

 - look into UV coordinates, should be indexed the same way as vertices, normals and faces are (instead of unrolled per each face)
 - look into HTML5 File API, binary blobs could help

The idea is that later there will be more loaders which would load different formats (like OBJLoader, ColladaLoader).

Usage (async JS):

var loader = new THREE.Loader();
loader.loadAsync( "obj/torus/Torus.js", function() { createScene( new Torus() ) } );

Usage (web worker):

var loader = new THREE.Loader();
loader.loadWorker( "obj/torus/Torus_slim.js", function( geometry ) { createScene( geometry ) } );

Web worker loader is useful for large meshes, where it allows browser to stay responsive for longer time and also it can handle larger meshes than async JS loader.

Web worker loader needs a simpler format of the model. Web workers can communicate with the main application only via message passing, where messages are JSON objects.

There is a new version of OBJ -> Three.js converter (convert_obj_threejs_slim.py) which can produce model in format needed for web workers.

All examples which were using models from OBJ converter were refactored to use Loader.

Except large mesh example, all examples are using just async JS loading. Web worker loading is there, it's just commented out, as it's a bit pain for local development.

Chrome doesn't allow to run web workers from pages accessed via file://, so you need either to run it with "--allow-file-access-from-files" flag, or access examples via local server (http://localhost/example.html).

Fixed ambient light computation in CanvasRenderer to get correct lighting when there is no ambient light specified in the scene.

Limitations:

 - Chrome can handle up to 5 lights in total (directional + point)
 - Firefox seems to handle up to 29 lights

These number are GPU specific (mine is ATI Mobility Radeon 3650).

This turned out to be quite tricky. The number of varying vectors in shaders is limited. Additionally Chrome and Firefox have different limitations (at least on Windows, probably due to Chrome using ANGLE as rendering backend).

Hence WebGLRenderer has hardcoded limit of maximum 5 lights.

WebGLRenderer constructor now takes (optional) scene argument, so that numbers and types of lights present in the scene can be used to generate minimal possible shader.

If no scene is passed, shader allowing 1 directional + 4 point lights will be generated.

* Minor fixes (Geometry normal calculation)
* Isolated Matrix3 code into `Matrix3.js`
* README and TODO updated

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.

* MeshBitmapUVMappingMaterial -> MeshBitmapMaterial. Second param is mode, which is THREE.MeshBitmapMaterialMode.UVMAPPING by default.
* Removed MeshFaceColorFillMaterial and MeshFaceColorStrokeMaterial
* Added MeshFaceMaterial ( it uses the face.material for that pass )
* CanvasRenderer and SVGRenderer per face material logic changed.
* SVGRenderer supports particles again.
* WebGLRenderer currently broken :/
* Code clean up

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

Extended CanvasRenderer to be able to handle decals (MeshBitmapUVMappingMaterials as secondary materials).

For decals you need to set "decalIndex" property of the material (corresponding to materials index of the original mesh UV material).

Added multimaterials example.

Fixed forgotten sphere smoothing in OBJ converter example.

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)