Merge branch 'BufferGeometry---fix-raycast-to-take-offsets-into-account' of git://github.com/insominx/three.js into dev

Summary:

BUGZID:
Summary:
This switches the "screen" variable to use the domElement's dimensions & location rather
than the window.

It also removes the "radius" variable in favor of using each dimension's value (ie
width & height)

Also switched plane creation method to take advantage of the existing
function setFromCoplanarPoints.

Also condensed a couple vector lines.

Raycasts now take BufferGeometry offsets into account.
Added a safeguard to check for the existence of color before adding them
to the intersected face.
Made a minor optimizations by moving a precondition out of the loop.

@gero3 reported that Matrix4.getInverse() was incorrect when the operand was the same as this.  Fixed with unit test.

Fix opening 'Creating a scene' page with 'edit this page'.

Added some info regarding the quaternion object, its applications and the purpose of its functions.
Added some info regarding the box2 object and its functions.

There are many allocations that would still need to be removed though.