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.

% Plot a shape using n points. Returns cell array of plot handles.
%   hs = plot_shape(s,n)
function hs = plot_shape(s,n)
    default_arg('n',100);

    hs = {};
    hold on
    for i = 1:length(s)
        hs{end+1} = grid.plot_curve(s{i},n);
    end
    hold off
end