This repository is intended to be used as a super project merged from two repositories.
All external dependencies are now included via the CMake FetchContent module available since version 3.11 instead of the old style project structure (Git submodules).
The original plan was to include C++20 module as part of the interface exposed, but the support of C++20 module is experimental in most of the toolchains (including compilers, IDEs and CMake itself). So the support of C++20 module has been dropped and only the legacy interface (C++ headers) will be provided.