Fixes for vertex/cell classes of SMDS_3 and Tetrahedral_remeshing (#7610

)

## Summary of Changes

The main point of this PR is to restore the API of
`Remeshing_cell_base_3` to the initial state (since CGAL 5.1), which was
changed with the introduction of SMDS_3 in CGAL 5.6
(#5693).

In CGAL 5.5, the class `Remeshing_cell_base_3` is templated by a geom
traits and a cell base.
In CGAL 5.6, the class became templated by only two index types,
removing the possibility to derive from custom (TDS) base cell types.

Also:
- Decompactify Simplicial_cell_base_3, allowing a cell base to be used
- Changed the API of Remeshing_vertex_base_3 to match that of
Remeshing_cell_base_3 (and other CGAL triangulations): a Gt and a Vb
- Proper rebind mechanism for VB/CB of SMDS_3 / Tetrahedral remeshing
- Various fixes of the SMDS_3 / Tetrahedral_remeshing doc.

TODO:
- [x] Announce the breaking changes in CHANGES.md
- [x] Introduce Compact_simplicial_cell_base_3?

## Release Management

* Affected package(s): `SMDS_3`, `Tetrahedral_remeshing`
* Issue(s) solved (if any): -
* Feature/Small Feature (if any): n/a
* License and copyright ownership: no change

Installation/CHANGES.md

@@ -35,6 +35,18 @@ Release date: October 2023
 -   Removed the class templates `Gray_image_mesh_domain_3`, `Implicit_mesh_domain_3`, and `Labeled_image_mesh_domain_3`
     which are deprecated since CGAL-4.13.
 
+### [Tetrahedral Remeshing](https://doc.cgal.org/6.0/Manual/packages.html#PkgTetrahedralRemeshing)
+-   **Breaking change**: The template parameters of
+    `CGAL::Tetrahedral_remeshing::Remeshing_cell_base_3`
+    have been modified, reverting changes introduced in CGAL 5.6.
+-   **Breaking change**: The vertex base of
+    `CGAL::Tetrahedral_remeshing::Remeshing_vertex_base_3`
+    must now be a model of the concept ` SimplicialMeshVertexBase_3` (and not only `TriangulationVertexBase_3`).
+
+### [3D Simplicial Mesh Data Structure](https://doc.cgal.org/6.0/Manual/packages.html#PkgSMDS3)
+-   **Breaking change**: The template parameters of
+    `CGAL::Simplicial_mesh_cell_base_3`
+    have been modified to enable passing a geometric traits and a custom cell base class.
 
 [Release 5.6](https://github.com/CGAL/cgal/releases/tag/v5.6)
 -----------

SMDS_3/doc/SMDS_3/Concepts/SimplicialMeshCellBase_3.h

@@ -4,14 +4,12 @@
 
 The concept `SimplicialMeshCellBase_3` describes the requirements
 for the `TriangulationDataStructure_3::Cell` type of the triangulation
-used in the 3D simplicial mesh data structure. The type `SimplicialMeshCellBase_3`
-refines the concept `TriangulationCellBase_3`
-and must be copy constructible.
-The concept `SimplicialMeshCellBase_3`
-includes a way to store and retrieve
-if a given cell of the triangulation is inside a subdomain or not,
-and which subdomain it belongs to
-in case of a multi-domain.
+used in a 3D simplicial mesh data structure.
+
+The type `SimplicialMeshCellBase_3` refines the concept `TriangulationCellBase_3`
+and must be copy constructible. The concept `SimplicialMeshCellBase_3` includes a way to store and
+retrieve if a given cell of the triangulation is inside a subdomain or not, and which subdomain it
+belongs to in case of a multi-domain.
 
 Moreover, this concept adds four markers per cell to mark the facets
 of the triangulation that are surface facets.

SMDS_3/doc/SMDS_3/Concepts/SimplicialMeshVertexBase_3.h

@@ -4,7 +4,7 @@
 
 The concept `SimplicialMeshVertexBase_3` describes the requirements
 for the `Vertex` type of the triangulation
-used in the 3D simplicial mesh data structure. The type `SimplicialMeshVertexBase_3`
+used in a 3D simplicial mesh data structure. The type `SimplicialMeshVertexBase_3`
 refines the concept `TriangulationVertexBase_3`.
 It provides additional members to store and retrieve
 information about the location of the vertex with respect

SMDS_3/examples/SMDS_3/c3t3_example.cpp

@@ -21,7 +21,7 @@ using Surface_patch_index = unsigned char;
 using Curve_index = char;
 using Corner_index = short;
 
-using Cb = CGAL::Simplicial_mesh_cell_base_3<Subdomain_index, Surface_patch_index>;
+using Cb = CGAL::Simplicial_mesh_cell_base_3<K, Subdomain_index, Surface_patch_index>;
 using Vb = CGAL::Simplicial_mesh_vertex_base_3<K, Subdomain_index, Surface_patch_index,
                                                   Curve_index, Corner_index>;