"A Hard Day's Night" captured Beatlemania as it was happening, and more than four decades later, it remains a peerlessly zesty rock 'n' roll fable. Director Richard Lester's jump cuts now seem exhilarating as Jean-Luc Godard's, John Lennon's wisecracks as well timed as Groucho Marx's. Yet this original Fab Four movie is innocent in a way no other later rock 'n' roll film could be, and much of the credit must go to the thousands of screaming teenage girls in the audience--the ones who's lips form such magical words as "John!" and "Paul!" and "George!" and "Ringo!" while tears stream down their cheeks. When