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?

Method from Ulrich Deiters, superancillary from our new paper

And JSON I/O

See #2

See #2

See #2