Add functions to compute the kernel of a mesh
## Release Management
* Affected package(s): `PMP`, `BGL`
* Issue(s) solved (if any):
* Feature/Small Feature (if any):
[Mesh_Kernel](https://cgalwiki.geometryfactory.com/CGAL/Members/wiki/Features/Small_Features/Mesh_Kernel)
* Link to compiled documentation (obligatory for small feature) [*wrong
link name to be changed*]()
* License and copyright ownership: GF
## Summary of Changes
This PR fixes the error reported in issue #781. The main two changes
are:
- in `Refine_edges.h`: allow the refinement point of a constrained edge
to be an existing close encroaching vertex,
- in `Refine_faces.h`: skip tiny bad faces when their bbox are smaller
than a few ulp.
## Release Management
* Affected package(s): Triangulation_2, Mesh_2
* Issue(s) solved (if any): fix#781
* Feature/Small Feature (if any):
* Link to compiled documentation (obligatory for small feature) [*wrong
link name to be changed*](httpssss://wrong_URL_to_be_changed/Manual/Pkg)
* License and copyright ownership: maintenance by GeometryFactory, now
copyright change
## Summary of Changes
New package for 3D barycentric coordinates in a convex polyhedron
## Release Management
* Affected package(s): New package
* Feature/Small Feature (if any):
[here](https://cgal.geometryfactory.com/CGAL/Members/wiki/Features/Barycentric_coordinates_3)
* Link to compiled documentation (obligatory for small feature) [*wrong
link name to be changed*](httpssss://wrong_URL_to_be_changed/Manual/Pkg)
* License and copyright ownership: GF
## TODO
- [x] check branch size (@sloriot)
- [x] check usage of `get_tolerance()` from
`Barycentric_coordinates_3/include/CGAL/Barycentric_coordinates_3/internal/utils_3.h`
fixed concepts (review)
changed Has_on_bounded_side_2/3 to require Segment_2, Iso_rectangle_2 and Iso_cuboid_3 to be fully inside the Circle_2/Sphere_3
Sébastien Loriot