Add depth function to materials

Reuse program when not changed

Add and remove semicolons

Fixes #6266

Resuse program if code is the same and material updated

CanvasRenderer: typo

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