Add redefined predicats in Periodic_labeled_mesh_domain_3.
(Do_intersect_surface and Construct_intersection.)
Mesh_3 has new protected member functions allowing its heirs to access the
labeling function and the error bound. Some private member functions
required in Periodic_labeled_mesh_domain_3 are set protected.
(Should be moved in a small feature modifying only Mesh_3?)
It can be built only with an Iso_cuboid_3.
It has a periodic_bounding_box member function required by periodic meshing
algorithms.
Periodic_implicit_mesh_domain_3 inherites from this new class now.
Periodic_implicit_mesh_domain_3 uses Implicit_to_labeling_function_wrapper as
default wrapper now.
Periodic cases need a periodic bounding box with exact coordinates.
So, Periodic_implicit_mesh_domain_3 can only built with an Iso_cuboid_3.
Moreover, the method periodic_cuboid is renamed periodic_bounding_box.
Aymeric PELLE