Faster mesh intersections

[BrunoLevy]

• interval_nt class in round_to_nearest mode
• interval_nt class in round_to_infinity mode (does not seem to be faster than round_to_nearest mode)
• filters for MeshInTriangle predicates
• filters for RadialSort
• Do radial sort in parallel
• random shuffle for better radial sort load balancing ?
• filter stats for radial sort
• radial sort by propagation
• CDT2d per-vertex predicate caching for constraint insertion (bof, won't do, not worth the additional complexity)
• Better management of predicate cache when inserting a duplicated vertex (begin_transaction() / end_transaction())
• Global vertices table: use symbolic information as vertex key instead of exact geometry
• Use local meshes instead of global vertices table then merge them (by sorting the vertices)

[Glizzy77]

Wack 💯💯