special chars trimmed in url_title()

The function url_title() trim special chars, ie url_title("El veloz murciélago hindú comía feliz cardillo y kiwi") returns "El-veloz-murcilago-hind-coma-feliz-cardillo-y-kiwi" and must be "El-veloz-murcielago-hindu-comia-feliz-cardillo-y-kiwi", this correction is partial,still missing special characters