merge/21 add parameters to optimize result

I recognized that sometimes it might be useful to know the value of the Newton norm or the equilibrium norm after a simulation has converged. I.e. I did a convergence test and wondered about the number of steps needed to reached different convergence criteria. Actually the reached convergence criteria is often far below the required one (tolerance given to the solver) and thus the actually reach tolerance might be useful. Therefore I would suggest to add the reached newton and equilibrium tolerance as members to the OptimizeResult object.