Issue for 2026 pre-RC (Incl. Qt6) notes

Note: As this is a long thread, let's hide any discussion which get split out into a separate issue, so that this discussion captures unresolved topics

As per https://github.com/openscad/openscad/issues/4909#issuecomment-3797100148

I raised this issue to stop pollution of that Qt6 issue.

I'm working my way through the examples, so far so good, except 2021 console message Loaded design 'C:/Program Files/OpenSCAD (Nightly)/examples/Old/example024.scad'. is not logged by 2026. It makes keeping track of which example I'm up to difficult. UPDATE: It is logged sometimes. As mentioned in #6163. [Fixed]

Starting with CGAL. I noticed on my favourite, old/example024 with n=4, 2026 used significantly less memory than 2021, 4.6GB v 5.9GB.