Python Interface in QM/MM Mode with sPuReMD: crash when calling cleanup without calling simulate

The code crashes if the cleanup function is called before calling the simulate function. Example using the Python interface:

handle = setup2(num_atoms, types, flat_pos,
            sim_box,
            ffield.encode(),
            control.encode())
ret = cleanup(handle)

It is not an urgent issue since things work fine if you follow the intended order.