Add lower level for boot-strapping to RungeKuttaExteriorRV - Add a lower level to RungeKuttaExteriorRV for which bootstrapping starts, e.g start bootstrapping from time level 3 using a 3rd order BDF - Clean up ResidualViscosity

% Plots all the eigen values for a sparse matrix.
function plotEig(A)
    e = eig(full(A));
    e = sort(e);
    plot(e,'.')
end