Remove the camera animation so that HMD orientation is applied correctly
and add a crosshair instead of mouse-based intersection.

This fixes things for Firefox since the latest builds include both an
Oculus device and a Cardboard device, even if you're on a desktop PC.

Added Gamma Correction Shader

Unnecessary parameter

Detach was taking a parameter that wasn't used. Removing it.

Lazy loading of variables in Matrix4

This allows rendering the same geometry with different WebGLRenderers.

BufferedGeometry Instancing

Added both intanced and non instanced interleaved bufferedGeometry

Do not generate mipmaps if render target generateMipmaps is not set.

This also fixes two examples that had generateMipmaps set to false but
requested LinearMipMapLinearFilter which after the changes results in
a WebGL error.

Fixes #6316