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

% 'left' | 'center' | 'right'
% 'baseline' | 'top' | 'cap' | 'middle' | 'bottom'
function place_label(pt,str,horzAl,vertAl)
    default_arg('horzAl','center');
    default_arg('vertAl', 'middle');

    x = pt(1);
    y = pt(2);
    h = text(x,y,str);
    h.HorizontalAlignment = horzAl;
    h.VerticalAlignment = vertAl;
end