current CAPI of CompilerEngine isn't really a CAPI. It's initial need
was for the python bindings to have access to the CompilerEngine through
a convenient API. So we now make a clear separation of CAPI and python
wrappers. So we now have wrappers functions, that can be implemented
using C/C++, and will be exposed to python via pybind11. And we have a
CAPI (still need fixing as it still contains C++ code), that can be used
as is, or to build bindings for other languages (such as Rust).
