add equals, clone to Box2, Box3, Plane and Sphere. Adopt +Inf/-Inf in Box2 and Box3 per @mrdoob'd recommendation.  Begin Box3 unit test.

Vector2: setX, setY, Vector4: setX, setY, setZ, equals.  Unit tests for Vector2, Vector3 and Vector4.

move away from static fromXXX-style constructors to setXXX style member functions widely used in ThreeJS.

Plane,Box3,Sphere improvements: static constructors, code simplficiation, optimizations.  Box3 made more robust via true empty (+MAX_VALUE,-MIN_VALUE).

implement Plane.js, add to common.js and update Frustum.js to use it instead of Vector4 - issue #2706

This got broken after GeometryLoader got removed, using instead JSONLoader.

Another step towards WebGLDeferredRenderer. It's still quite a mess but at least now code lives outside of the examples (and is reusable, to a degree).

These are first steps toward WebGLDeferredRenderer. This will take a while.

Not needed now that these are in G-Buffers.

This allows to have different per-object Phong materials in deferred shading.