Merge branch 'dev' into refactor_flexible_skinning

Conflicts:
	build/three.js
	src/extras/animation/Animation.js
	src/objects/Skeleton.js
Reverted three.min.js.
Reverted three.min.js to the version stored in dev.
Update BoundingBoxHelper.html

Changed incorrect example from ArrowHelper with appropriate BoundingBoxHelper example.
Merge pull request #4939 from iras/patch-2

Update BoundingBoxHelper.html
Minor improvement.
Merge remote-tracking branch 'origin/dev' into dev
Converted CrosseyedEffect to StereoEffect.
That's the output firefox wants: https://air.mozilla.org/virtual-reality-the-future-of-the-web/
Added CanvasRenderer StereoEffect example.
CanvasRenderer still needs some sort of masking...
SVGRenderer: Implemented @srifqi clearAlpha code. Fixes #4898.
SpritePlugin: Fixed default texture.
Updated builds.
StereoEffect: Support cameras with parents.
Update ShadowMapPlugin.html

Fixed links to WebGLRenderer
Simplified DeviceOrientationControls.
Simplified CSS3D Sprites example.
Simplified DeviceOrientationControls a bit more.
Merge pull request #4944 from person594/patch-1

Update ShadowMapPlugin.html
Simpler StereoEffect.
Merge pull request #4900 from drakh/dev

DigitalGlitch postprocessing effect