And some tests

Can also specify them as JSON-formatted string, to make fitting a bit easier, for instance

And get the parameters from the class

* Try to break up the C++ interface into smaller chunks

In order to make compilation less RAM intensive

* Inline the makers, also add the other sources

* Tidying up the splitting

Problem was mcx missing sqrt

Recommended by static analysis in Xcode

(no implicit conversion of nlohmann::json to filesystem)

Makes it same as base model

Closing in with the models

Gets very close to what is needed for property Jacobian

Everything seems pretty promising aside from the mutant, which requires additional thought. How can we store the mutant in AllowedModels