## Summary of Changes
Replace a `std::set<Vertex_handle>` by a
`std::set<std::pair<std::size_t,Vertex_handle>>` to make traversing the
set deterministic.
At the same time, do not `erase()` a key, but an `iterator`.
## Release Management
* Affected package(s): Mesh_2
* Issue(s) solved (if any): fix#8719
* License and copyright ownership: unchanged
It is not clear to me that this is the right thing to do:
- it is done for some classes
- but in some test, a comment mention that it should be uninitialized
(the test works if init to -1 but not to 0).
- Base_time_stamper is doing an init to -2
That will suppress the warnings about `CMP0167` (from CMake 3.30):
```
CMake Warning (dev) at cmake/modules/display-third-party-libs-versions.cmake:37 (find_package):
Policy CMP0167 is not set: The FindBoost module is removed. Run "cmake
--help-policy CMP0167" for policy details. Use the cmake_policy command to
set the policy and suppress this warning.
```
- remove all mentions of `Edge` and `Constraint`
- `Subconstraint_iterator` is renamed `Subconstraint_and_contexts_iterator` (because of its value type)
- a new `Subconstraint_iterator`, with value type `Subconstraint`
- a few unused/untested and uncompilable functions are removed from the code
- a lot of internal renamings
== Breaking changes ==
For `Constrained_triangulation_plus_2`, there are a few breaking changes...
- The value type of `subconstraints_begin()`, `subconstraints_end()`, of the range `subconstraints()` has changed to `Subconstraint` (a simple `std::pair` of vertex handles). That is actually a kind of bug-fix, because it was documented as such in the user manual.
- The new member functions `subconstraints_and_contexts_begin()`, `subconstraints_and_contexts_end()`, `subconstraints_and_contexts()` are created get the old value type (`std::pair<const Subconstraint, std::list<Context>*>`).
- A few range types have changed from `CGAL::Iterator_range<It>` to `unspecified_type`, for efficiency reasons.
- Doc fixes.
== Determinism ==
Even if it was not documented, the range `subconstraints()` is deterministic (used by Mesh_2), and `subconstraints_and_contexts()` is not.