Create residual viscosity package +rv and generalize the ResidualViscosity class - Generalize residual viscosity, by passing user-defined flux and calculating the time derivative outside of the update. - Create separate RungekuttaRV specifically using interior RV updates - Separate the artifical dissipation operator from the scheme AdvectionRV1D so that the same scheme can be reused for creating the diff op used by the ResidualViscosity class

function e = error2d(discr, v1, v2)
    % If v1 and v2 are more complex types, something like grid functions... Then we may use .getVectorFrom here!
    h = discr.h;
    e = sqrt(h.^2*sum((v1-v2).^2));
end