Fix initialisation issues in Mesh_3

[MaelRL]

Summary of Changes

• Issue 1 (fbecb18): bad comparison in minimal weight clamping in 2D case, caused protection balls to become hidden.
• Issue 2 (39c0a9f): robust intersection traits returned no intersection for a ray spawned within a triangle, so the init_c3t3() could not insert initial points.
• Issue 3 (49bb14b): in the 2D case, the code was exiting too early while adjusting ball sizes before a new point insertion.
• Issue 4 (1f258bc): after 39c0a9f, initialization did not work anymore if the source is on the domain.

Release Management

• Affected package(s): Mesh_3
• Issue(s) solved (if any): -
• Feature/Small Feature (if any): -
• License and copyright ownership: no change

[sloriot]

Runtime errors in CGAL-6.0-Ic-13 in Generator package (at least)

Built target random_points_on_tetrahedral_mesh_3
terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: c3t3.triangulation().dimension() >= 2
File: /home/sloriot/CGAL/git/integration/Mesh_3/include/CGAL/make_mesh_3.h
Line: 464
Aborted

[MaelRL]

@janetournois @lrineau That's actually the configuration that we were discussing: the source of the ray being shot in the C3T3 initialization is a point exactly on the domain. Beforehand, it would find another intersection; now, source of the ray is returned whatever the ray direction, and the initialization only spawns a single point.

[MaelRL]

This PR should be finished now.

Other issues are related to edge protection and will be handled in a different pull request.

[lrineau]

Tested in https://cgal.geometryfactory.com/CGAL/testsuite/results-6.0-Ic-27.shtml

[lrineau]

This PR was merged into 5.5.x-branch (too late for 5.5.3 though).