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.

% [x,h] = get_grid(a,b,m)
function [x,h] = get_grid(a,b,m)
    % TODO: allow the interval to be a vector
    x = linspace(a,b,m)';
    h = (b-a)/(m-1);
end