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)

@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.

Split /src/extras/core/Curve.js to
/src/extra/curves/*

LineCurve
QuadraticBezierCurve
CubicBezierCurve
SplineCurve
EllipseCurve
ArcCurve
LineCurve3
QuadraticBezierCurve3
CubicBezierCurve3
SplineCurve3
ClosedSplineCurve3

Summary:
BufferGeometry allows faster loading (direct buffer loading)
but not ray casting.  This adds that (if it is dynamic)

WebGLRenderer3: Added normals, programs cache, fallback for program compiled with errors and basic support for ShaderMaterial.