V8.0.0 beta ready for testing

[Ian Bell]

Dear CoolProp users,

Thanks to Claude Code's help, and contributions from generous humans, a beta release of version 8.0.0 of CoolProp is ready for testing. Most corners of the library have been touched, and some longstanding issues (some open for more than a decade!) have been closed. This is a major version bump since there are some breaking changes, but I have tried to limit the blast radius and retained backwards compatibility where possible.

Highlights of the changelog are here: https://coolprop.github.io/devdocs/coolprop/changelog.html . 

I am personally most excited about:

* Massive improvement to reliability of mixture calculations -- implemented the algo of Michelsen

* MUCH faster and reliable h,s inputs for pure fluids

* SVDSBTL tables (memory efficient, accurate, and fast)

* A cross-platform native GUI

* Python interface is now mostly nanobind

* rapidjson replaced by nlohmann::json

The dev docs are here: https://coolprop.github.io/devdocs/coolprop

Report any issues you experience here: https://github.com/CoolProp/CoolProp/issues

$$ Show your support by becoming a sponsor: https://github.com/sponsors/CoolProp $$

Cheers,

Ian