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

% Creates a periodic discretization matrix of size n x n
%  with the values of val on the diagonals diag.
%   A = stripeMatrix(val,diags,n)
function A = stripeMatrixPeriodic(val,diags,n)

    D = ones(n,1)*val;
    A = spdiagsPeriodic(D,diags);
end