Based largely upon: https://pubs.acs.org/doi/abs/10.1021/acs.iecr.1c04703

Fix the parametric tracer; it was switching directions because the dot product check was not implemented properly.

TODO: add some tests to ensure this stays fixed, maybe P-R for CO2+ethane?

TODO: apply polishing in another variable if constant composition polishing fails

Switch critical tracing to use one of the molar concentrations as the fixed parameter when polishing

Expose more critical methods in pybind11 interface

I think g++ getting confused by copy elision on return of Eigen temporary?