Quasi_static_Finite_strain_Quasi_incompressible_ViscoElasticity still uses old way to filter for cells with DataOut

[bangerth]

This program still uses the old way to select which cells to produce output on:

  template<int dim>
  class FilteredDataOut : public DataOut<dim>
  {
  public:
    FilteredDataOut (const unsigned int subdomain_id)
      :
      subdomain_id (subdomain_id)
    {}

    virtual ~FilteredDataOut() {}

    virtual typename DataOut<dim>::cell_iterator
    first_cell ()
    {
      auto cell = this->dofs->begin_active();
      while ((cell != this->dofs->end()) &&
             (cell->subdomain_id() != subdomain_id))
        ++cell;
      return cell;
    }

    virtual typename DataOut<dim>::cell_iterator
    next_cell (const typename DataOut<dim>::cell_iterator &old_cell)
    {
      if (old_cell != this->dofs->end())
        {
          const IteratorFilters::SubdomainEqualTo predicate(subdomain_id);
          return
            ++(FilteredIterator
               <typename DataOut<dim>::cell_iterator>
               (predicate,old_cell));
        }
      else
        return old_cell;
    }

  private:
    const unsigned int subdomain_id;
  };

This needs to be updated.