- Rewrite all Python features to use the pybind11 library instead of boost::python.
Unlike boost::python, pybind11 is a header-only library that is just included by Pyosys code, saving a lot of compile time on wheels.
- Factor out as much "translation" code from the generator into proper C++ files
- Fix running the embedded interpreter not supporting "from pyosys import libyosys as ys" like wheels
- Move Python-related elements to `pyosys` directory at the root of the repo
- Slight shift in bridging semantics:
- Containers are declared as "opaque types" and are passed by reference to Python - many methods have been implemented to make them feel right at home without the overhead/ambiguity of copying to Python and then copying back after mutation
- Monitor/Pass use "trampoline" pattern to support virual methods overridable in Python: virtual methods no longer require `py_` prefix
- Create really short test set for pyosys that just exercises basic functionality
- cibw now builds and uses bison 3.8.2 explicitly on platforms with no or out-of-date bison — AlmaLinux 8 only goes up to Bison 3.0
- cibw environment now includes `OPTFLAGS=-O3` to avoid generating debug info for abc, saving space in memory during linking
- setup.py attempts to build `yosys-abc` independently first to avoid memory pressure from gigantic abc link step running in parallel with something else
