Add render depth buffer to texture.

Expand CC3GLTexture2D texture format options to include depth formats. Add rendering
of depth buffer to a texture, and visualization of the depth buffer to CC3DemoMashUp.
Simplify creating and managing off-screen surfaces.

Add CC3GLFramebuffer colorTexture and depthTexture properties. Add size property
to CC3GLFramebuffer. Attachments created without size and resized when added to
framebuffer. Depth attachment with stencil auto-attached to stencil attachment.
Add CC3GLViewSurfaceManager properties to extract texel format and type from
renderbuffer formats.
Simpify scene drawing building blocks.

Move utility mesh node subclasses to new CC3UtilityMeshNodes.h file.
Move shouldDrawInClipSpace to CC3Node from CC3NodeDrawingVisitor. Move drawing
visitor init from scene to visitor. Check max size of textures and renderbuffers.