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.

function A = kr(varargin)
    n = nargin;

    A = 1;

    for i = 1:n
        A = kron(A,varargin{i});
    end
end