Refactor what is implemented
Fix bug in Ar10
The functions for multi-fluid model need to be rewritten to build a temporary array, multiply by mole fractions, and sum.
Tracing is now crazy fast
Bug in mcx with negative arguments to pow(x,2.0), square fixes it
Polishing missing still, otherwise done?
Doesn't work so far
Not especially fast
Lots of testing remains for other numerical types
