In a movie where flying metal meets flying metaphors, “Iron Man 3” is like rooting for a good hammer. Billionaire playboy industrialist Tony Stark makes it possible to pilot a fleet of Iron Man outfits by remote control, while he munches In’N’Out burgers miles away. “Iron Man” has become “Iron Drone.” The real metaphor here is the empty suit. Among the faithful, that change won’t lead to tears for teenage theater hands to soak