this is necessary because some older simulations only provide the
full-fledged solver class but no physical model.
(also, this allows to use something else than the standard newton
solver.)
so, far it is just a copy of the old "SimulatorFullyImplicitBlackoil"
class (which became a simple forward to the base class). The intention
is to unify the common simulator code in this class to avoid excessive
copy-and-pasting.
