TO DO: *NeedsUpdate, CustomAttributes, Skinning, MorphTargets.

Remove unneeded function calls, rearrage for fused multiply–add, remove
excessive shader whitespace

Added both intanced and non instanced interleaved bufferedGeometry

add ambientocclusion glsl shaders.  Separate out uv/uv2 vertex and fragment shaders to make things cleaner.

Hardware instancing using ANGLE_instanced_arrays for BufferedGeometry

adopt common.glsl shader utilities across all shaders where applicable.  Fix vec*matrix bug in envmap_fragment.glsl

(three.js issue: #5552) add BinaryTextireLoader.js, RGBELoader.js (plus example), TGALoader.js extends BinaryTextureLoader.js

Also trying to only call gl.getExtension() when needed.

Object3D instace to be used for skinning--not just Bone instances.  Furthermore,
this commit removes the restriction that a SkinnedMesh can only be skinned by
child objects/bones.  Now, a SkinnedMesh can reference arbitrary objects for the
purpose of skinning.  One implication of this is that Bone.skinMatrix has been
removed as it is no longer necessary.

Here is a breakdown of the notable changes:

src/extras/animation/Animation.js
* Fixed animation of non-bones
* Removed references to skinMatrix

src/extras/animation/AnimationHandler.js
* Removed special handling of SkinnedMatrix instances

src/extras/animation/KeyFrameAnimation.js
* Removed special handling of Bone instances
* Removed references to skinMatrix

src/extras/helpers/SkeletonHelper.js
* Removed references to skinMatrix and Skeleton

src/objects/Bone.js
* Removed references to skinMatrix

src/objects/Skeleton.js
* Removed entirely, refactoring functionality back into SkinnedMesh

src/objects/SkinnedMesh.js
* Re-added code to construct the skeleton hierarchy when it is present in the geometry object that is passed to the constructor.  This is here for backwards compatibility and could be refactored at a later time.
* Added bind() function that takes an array of bones (Object3D instances) that are used to skin the mesh.  This function establishes the initial bind transforms of the mesh and bones.
* Added initBoneInverses() function that is used internally by bind() to calculate the bind matrices.
* Added initBoneMatrices(), which contains refactored code that previously existed in the constructor (prior to the THREE.Skeleton refactor).  This code sets up storage for the bone matrices and/or texture.  It is used internally by bind().
* Added updateBoneMatrices(), which is called by the renderer after the scene's world matrices have been updated.  This is done in a separate pass because SkinnedMesh can depend on objects that are stored anywhere in the scene hierarchy, not necessarily child objects.

src/renderers/WebGLRenderer.js
* Call updateBoneMatrices() on SkinnedMesh instances after world matrices have been updated
* Removed references to Skeleton