MGTwoLevelTransferNonNested: simplices with multiple components

[peterrum]

No description provided.

[fdrmrc]

Thanks @peterrum! I changed the logic in following snippet so that dof_handler_support_points doesn't distribute dofs twice (with simplices and degree>0).

//dof_handler_support_points defined above
          if (fe.reference_cell().is_simplex())
            dof_handler_support_points->distribute_dofs(fe.base_element(0));
          if (degree == 0)
            dof_handler_support_points->distribute_dofs(
              FE_DGQ<dim, spacedim>(degree));
          else
            dof_handler_support_points->distribute_dofs(
              FE_Q<dim, spacedim>(degree));


          return dof_handler_support_points;

While there, I've templatized the Operator with n_components in order to add a test with multiple components.

[peterrum]

This is ready from our side. @fdrmrc has done some elasticity simulations with this already.

[fdrmrc]

I confirm I've used the present PR for different tests and everything runs fine.