A MATTER OF MILLIONS THE Clipper smacked the blue of Biscayne Bay and settled into a lazy squat, from which it taxied toward a landing. An audible sigh of relief came from the roped-off crowd that lined the shore of Dinner Key. Little wonder that the sigh was heard, for the throng was immense. Seldom did the population of Miami, citizen and tourist, assemble en masse at the Marine Airways Ba