Added support for parallel dune-istl solvers

    To support this the solveSystem methods of the LinearSolverInterface gets
    an optional additional template parameter of type boost::any. It can hold an
    copy constructable object. In our case it is used to pass the information ab
    the parallelization into the solvers of dune-istl without the compiler needi
    their type. Inside of LinearSolverIstl::solveSystem we check whether the typ
    boost::any is the new ParallelIstlInformation. If this is the case we extrac
    and use the parallel solvers if available, otherwise we solve serial/sequent
    
    The new ParallelIstlInformation is needed as the OwnerOverlapCopyCommunicati
    constructable. This is indeed a design flaw that should and will fixed upstr
    time being we need ParallelIstlInformation to transfer the ParallelIndexSet 
    objects.