Various C++20 tweaks

[Capital-Asterisk]

I'm not sure if there's a noticeable change in my views, but I'd like to enforce "no \<ranges>" for the time being. It's...

• something I personally don't want to work with. I don't like using authority, but I'm the one writing the majority of the code.
• doesn't fulfill any 'requirements' nor improves the code (besides ranges compatibility itself)
• sets the bar quite high for required C++ knowledge for potential contributors. The project architecture is already kind of weird, which I believe is a requirement to represent the rocket-science stuff with the least moving parts. Unnecessarily advance C++ will make explaining it even more difficult.

Many other C++20 features, like concepts, I'm perfectly cool with.

[jonesmz]

I'm not sure if there's a noticeable change in my views, but I'd like to enforce "no " for the time being.

Sure, we can do that.

I think it's pretty clear that I don't share the same opinion, but i don't mind the rule overly much.