Include GLTF2 exporter in examples

WWOBJloader2 only applying first texture

GLTF2 Exporter

GLTF2Loader: Top-down loading for textures, buffers, and bufferviews.

fix: `object` is not declared

GLTF2Loader: Remove unused shader extension.

GLTF2Loader: fix drawMode

GLTF2Loader: add support for points primitive

Update how to check if argument is canvas in getDataURL() of Texture

Optimize GPUParticleSystem shader

ColladaLoader2: Handling missing material definitions

Examples: Clean up

Replace checking if image has to DataURL with checking if image is instanceof HTMLCanvasElement in getDataURL() of Texture

Support embedded base64 texture image data in FBX ascii file

Added n-gon support to OBJLoader2

Removed the need for slashes and face buffer. Only buffer and simple attributes are parsed to processLine function due to simplified face detection algorithm