“Don't throw the past away. You might need it some rainy day. Dreams can come true again, when everything old is new again.” So go the lyrics to one of the late Peter Allen’s songs, which he once performed on the stage of the Radio City Music Hall, joining the Rockettes’ kickline in the process, the first man ever to do so. Allen’s characteristic flamboyance shouldn’t obscure the fundamental truth of his lyrics. Sooner or later, it seems, what was dated is suddenly current, whether the flip