Add support for artificial viscosity to the 1d burgers scheme. - Add support for artificial viscosity by parametrizing the discretization operator and boundary closure on the viscosity. - Add a time stepper which evaluates and updates the residual viscosity of the solution.

function benchmark(func, N)
    default_arg('N',100);

    tic
    profile on

    for i = 1:N
        func();
    end

    profile viewer
end