BACK TO THE FUTURE;HE WAS COOL IN THE '70S, GOT DISTRACTED IN THE '80S AND NOW HE'S BACK IN THE '90S, BEARING DOWN ON THE MILLENIUM WITH A COOL, MATURE GAZE AND A SELF-ASSURED STYLE. AFTER 25 YEARS OF DIRECTING COMMERCIALS, BOB GIRALDI HAS NOTHING TO PROV