Improve generalization in energy calls

[chemphys]

As the code is today, the monomer information, polynomial coefficients, and so on, are hardcoded inside the classes and the code. We should find a way to generalize that, so adding a new monomer does not imply changing the source code and recompile.

[fpaesani]

I think we should optimize this part in such a way that this information is passed at the input level so that the user has the possibility to change it.

[chemphys]

I think we can use something like what we have for the potentiall fitting repo. Have a configuration file, that will basically be a polynomial, charges, masses, or whatever the code needs.