* Feature: Add vertex color alpha channel support.

* Vertex alpha: Remove hasVertexAlpha from BufferGeometry

* WebGLRenderer: Do not run window.rAF when in XR.

* WebGLRenderer: Enhance dispose().

* Update builds.

* GPGPU Protoplanets example: fix pixel trails

* webgl_gpgpu_water.html: Remove mention to orbiting the camera.

* Keep instanceColor for InstancedMesh in toJSON and ObjectLoader

* instanceColor ignored if not present

RoughnessMipmapper created a new texture and replaced existing material
textures with the copy - however, the copy didn't inherit the UV
transform properties from the source.

This could be problematic when for example the roughness map came from
the glTF file that used KHR_texture_transform extension. When rendered
with standard three.js material this by itself would not be a problem
since three.js only supports one shared transform for most material maps
but when the user overrode the material with a custom one (which
happens inside model-viewer as far as I can tell), the incorrect
offset/repeat values in the cloned texture could result in incorrect
rendering.

* Sphere: Add expandByPoint() and union().

* Tests: Clean up.

* Fix some picking/raycast examples for touch devices

TrackballControls and OrbitControls listen to pointer events, which can cause mouse events not to fire on Android devices. Fix some picking examples by listening to pointer events in them as well.

* Remove mousemove listeners from examples using pointermove

They're redundant - all modern browsers support pointer events.

* fixed illegal feedback

* x === true .. over Boolean(x)

* toggle reflector externally

* rm comments

* add empty lines

* expose `.color` on reflector

* use accessor for `.color`

* fixed illegal feedback

* toggle reflector externally

* rm comments

* add empty lines

* expose `.color` on reflector

* use accessor for `.color`