Matrix4 .multiplyToArray: Clean up

Docs: Fix navigation panel responsivity

fixed webgl_interactive_instances_gpu example

Initial version of the shader preloader

Corrected typo in doc for Matrix4.extractBasis

WebGLShadowMap: cleanup and optimization

This reverts commit 8c72ccc7.

Update Cloth.js

BoxHelper: More consistent API

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