Improvements:
- Support for building and testing using CMake
- Fix old assertion errors so debug builds work again
- Support for building with the nvc compiler
- Support for building/running with the LLVM address and memory sanitizer enabled
- Fix a longstanding deadlock in the IO worker pool when running with the sherwood threadqueue
- Clear away various additional sections of dead code
Removals:
- Removed support for building using Autotools
- Drop regular testing for clang 11-13