## Summary of Changes
Fix issue #9058.
In `CGAL::Delaunay_triangulation_2`, replace thread_local vectors by
`std::array` on the stack.
## Release Management
* Affected package(s): Triangulation_2
* Issue(s) solved (if any): fix#9058
* License and copyright ownership: no change, maintenance by
GeometryFactory
## Summary of Changes
cosmetic improvements of CMake outputs
### set `FOLDER` for sub-directories of CGAL
In VS Code, the CMake project outline is much cleaner if CGAL is
configured with examples and demos:
<img width="416" height="574" alt="Screenshot_20250911_154221"
src="https://github.com/user-attachments/assets/f39f4ea5-317b-4f2d-ba75-e04691674c27"
/>
### set `CMAKE_MESSAGE_INDENT` to indent the outputs in sub-folders
The output messages from sub-directories are indented, now:
```
== Generating build files for examples ==
-- Configuring examples in examples/AABB_tree
-- Configuring examples in examples/Advancing_front_surface_reconstruction
-- Configuring examples in examples/Algebraic_foundations
-- Configuring examples in examples/Algebraic_kernel_d
NOTICE: This project requires the MPFI library and GMP support, and will not be compiled.
-- Configuring examples in examples/Alpha_shapes_2
-- Configuring examples in examples/Alpha_shapes_3
-- Configuring examples in examples/Alpha_wrap_3
-- Configuring examples in examples/Apollonius_graph_2
-- Configuring examples in examples/Arrangement_on_surface_2
-- Boost include dirs: /usr/include
-- Boost libraries:
-- Using gcc version 4 or later. Adding -frounding-math
-- Configuring examples in examples/BGL_LCC
-- Configuring examples in examples/BGL_OpenMesh
-- Configuring examples in examples/BGL_arrangement_2
-- Configuring examples in examples/BGL_graphcut
-- Configuring examples in examples/BGL_polyhedron_3
## Summary of Changes
The `read_..._WKT()` functions have `bool` as return type, but currently
only check if the stream is bad, which is not the case if no input was
read.
This PR was triggered by the fact that CGALlab could not WTK files with
polygons, but only polylines. It now can read polygons, but does only
draw the contours and not the interior.
## Release Management
* Affected package(s): Stream_support
* License and copyright ownership: unchanged
## Summary of Changes
### Todo
In the issue I had questions to @soesau and @janetournois
## Release Management
* Affected package(s):
* Issue(s) solved (if any): fix#9039
* License and copyright ownership: unchanged
`std::iterator_traits` requires that the iterator type defines all five nested types.
I have also modified the implementation of
```c++
make_prevent_deref_range(Range)
```