GPUParticleSystem: Dynamic attribute and stats.js

Revision of scene animation example

(reEdit)Add xfileloader

:file reading like parser. Can now read more (X)files.

Docs: References to MultiMaterial removed

ShaderChunk: dithering_pars_fragment now using common rand() and removed unneeded constant. See #11076.

Improve introduction doc fixing small scope issues

Small issues:
- Missing `var` keywords
- Multiple left-hand assignments declaring global variables, more info: http://stackoverflow.com/questions/1758576/multiple-left-hand-assignment-with-javascript

Fix Adaptive Tone Map issue on very dark (initial) scene

fix comparison with -0 in Math.js

fix operator precedence bug in WWOBJLoader2.js

Examples: Clean up

WebVR: Update origin trial token

Editor: Removed references to SceneLoader

OrbitControls: clean up

[glTF] Enable vertex colors on materials.

Update material.py

[examples] Remove unused lines from webgl_postprocessing_outline.html

Blendmesh example without alerts

Optimized version of LTC Area lights