FBXLoader: refactor genGeo method

Fbx loader split monolithic parseScene method

ColladaLoader: Added possibility to manually set path

FBXLoader: parse layered textures

Update ImageLoader.html

GLTFExporter: Use utf-8 encoding for .glb JSON chunk.

Update Texture.html

ImageBitmapLoader: Added documentation

GLTFExporter: Handle .flipY on textures.

Docs: Example of setURLModifier, IE11 note on GLTFLoader.

Docs: CubeTextureLoader Clarification

ImageBitmapLoader: Clean up

Add the ability to specify an alternative Object3D to the camera to apply the pose coming from a VRDevice

GLTFExporter: Export textures as data URIs.