- Skin_surface_refinement_traits->Skin_surface_subdivision_policy (subdiv,policy)
- Sqrt3->subdiv
- refinement->subdivision
- Put quadratic surfaces in a list and free the list on destruction
- Remove 'small' edges from the triangulated mixed complex


OLD:
- check the normals to the skin surface
- give surface_test input
- check triangulate_mixed_complex: converter not from traits
- polyhedron traits does not define Vector
- Chew's algorithm

Documentation:
- Add references from doc_tex/Skin_surface_3 to classes.
- Compute anchor point types are not from Skin_surface_traits
  since they depend on the regular triangulation and not the reg. kernel
