* Added `scene.ambientColor` and `Scene` now ignores `AmbientLights` (transferring hex for temporal backwards compatibility)
* CanvasRenderer and SVGRenderer using `scene.ambientColor`. Tried to update `WebGLRenderer` too, but the method in question doesn't seem to have access to the scene :S
* Removed `scene.origin` and updated examples that used it.
* Improved subdivision example

I could have just used `lookAt( scene.position )`, but eventually I would like to have Scene not extending Object3D.

* Camera is now a base object. PerspectiveCamera should be used instead. Figured out a way to show a warning when misused.
* OrthoCamera is now OrthographicCamera.
* Removed `target` from Camera.

Misc
* Renamed Trident to Axes.

* Camera.useTarget is now false by default. Updated some of the examples. I tried to remove target altogether (and use lookAt every frame), but I found that WebGLRenderer's ShadowMaps uses a camera with target. Will try again at some point.
* Object3D.lookAt now checks if it's a Camera and does the inverted view.
* Quaternion glitch reported at #595
* Added .name to Material
* WebGLRenderer .clear() to .clear( color, depth, stencil ). All of them true by default.

Hopefully this fixes several problems:

- ambient component not modulated by scene ambient light
- specular component not getting light colors
- unnecessary opacity use in lighting calculations
- unnecessary vertex shader light computation for Phong
- unnecessary use of one varying in Phong

Hopefully no more deprecation warnings.

Cleaned up some more examples.

This buggy pattern ("something = parameter || nonzero value") exists at more places though elsewhere setting to zero doesn't make that much sense (e.g. in geometries).

Not sure if we should change it everywhere to proper pattern ("something = ( parameter !== undefined ) ? parameter : value").

Maybe it would be good for establishing habit. I remember fixing this buggy pattern long ago but it just keeps popping up.

Fixed GeometryUtils.merge (normals and centroids weren't being multiplied)
Fixed misc_lookat and misc_ubiquity_test examples.

This allows, for example, better integration of additively blended materials with a regular scene.

Not to be confused with depthTest (which controls complete access to depth buffer, including reading).

Also messed up a bit with particle emitter example.

Simplified `Trident`.
Added `setX`, `setY`, `setZ` methods to `Vector3`. They're handy for oneliners (see `CylinderGeometry`).

`renderers/Projector.js` > `core/Projector.js`

`extras/geometries/Curve.js` > `extras/core/Curve.js`
`extras/geometries/CurvePath.js` > `extras/core/CurvePath.js`
`extras/geometries/Path.j`s > `extras/core/Path.js`
`extras/geometries/Shape.js` > `extras/core/Shape.js`
`extras/geometries/TextPath.js` > `extras/core/TextPath.js`