cam_culling demo

Camera culling defining if points, edges and faces are visible. This is feature is implemented in a modifier providing variable subdivision.
Modifiers
- Camera Demo : culling demo on the 3 domains : points, edges and faces
- Camera Projection (Group): computes positions which are visible or not
- Camera Point Culling : removes points which are not visible
- Camera Edge Culling : removes edges which are not visible
- Camera Face Culling : removes faces which are not visible
- Multires Surface : Multi resolution surface
- Multires Faces : multi resolution faces
- DEMO Multires Faces : a demo of Multires Surface
