handle Mr in the statepace function
in statespace implementation, adapt the code so that Mr is also compute with linearMatrice function. This should be done based on what is done in the modal module (just before state space call).
handle Mr --> done
use compute_uxd in a more clever way by setting mbs_data->Nux to zero temporarily.
--> It is interesting for the equilibrium because there are just the equil_fct and jacobian of different sizes. In modal, there is memory allocation at different levels...
move back the lpk module initialization in the new modal part or at least find a way to access its options !