Poisson reconstruction - experiments and speedup using parallel Mesh_3

[janetournois]

Summary of Changes

Describe what your pull request changes to CGAL (this can be skipped if it solves an issue already in the tracker or if it is a Feature or Small Feature submitted to the CGAL Wiki).

Release Management

• Affected package(s):
• Issue(s) solved (if any): fix #0000, fix #0000,...
• Feature/Small Feature (if any):
• Link to compiled documentation (obligatory for small feature) wrong link name to be changed
• License and copyright ownership:

[sloriot]

If might be interesting to look again at #4996 (in term of runtime + still crashing)

[sloriot]

Successfully tested in CGAL-6.0-Ic-129

[sloriot]

Is this branch still experimental or fixes done already a good addition to have?

[MaelRL]

We have another potential improvement in the pipeline, and I would rather keep it all in the same branch.

[sloriot]

Would that invalidate any of the fixes here?

[MaelRL]

Potentially yes, it's still related to hints.