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 printExpr(expr)
    result = evalin('caller',expr);
    fprintf('%s => %s\n', expr, toString(result));
end