fzero_vec, integral_vec and spline are now local functions in Curve. Renamed arcLengthStretch to arcLengthParametrization. Removed plot_derivative. Added some comments and extra lines + removed unneccesary lines. arcLength is now a method and not static. Constructor does not accept difference operator anymore.

% Discretises a shape such that points on the curves are no further than h appart.
function p = shape_discretise(s,h)
    p = [];
    for i = 1:length(s)
        [~,pt] = grid.curve_discretise(s{i},h);
        p = [p, pt];
    end
end