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 r = rowVector(v)
    if  size(v,1) == 1
        r = v
    elseif size(v,2) == 1
        r = v';
    else
        error('v is not a matrix');
    end
end