Work in progress refactoring ClickResolver.js to Ray.js

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

* Clickresolver.js: Implemented blackpawn's point in triangle algos ( http://www.blackpawn.com/texts/pointinpoly/default.html ). Now works properly with Face3 too.

Now we just need to make sure geometry.computeCentroids() is called at the end of creating/modifying the geometry, otherwise things break...

* Projector.js: Rather than calculating the screen space centrium of each face per render, seemed smarter to just project the precomputed centrium. Side effect: Polygon shaking is gone \o/

Added face culling to WebGLRenderer (default is now backface culling on, front face is counter-clockwise).

Thanks to mrdoob for noticing :)

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.

* Added `camera_orthographic` example.

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

Changed OBJ -> Three.js converter to use new materials system (eventual old models need to be reconverted).

Limitations:

  - one use case is now much slower
    - when a mesh has each face with different color (e.g. polyfield in examples/test.html)
    - before this used FaceColorFill material and in WebGLRenderer it was rendered fast with color attribute array
    - now when FaceColorFill material is gone, each face gets own VBO :(

  - material sorting uses Materials "toString" methods for hashing, so it's very important to keep these in a good shape

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.

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

* 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

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).

There were two problems:

- vertices were in a different coordinate system than normals
- generated JS code was not properly handling normals with 0-sized components