BALLET As a kid I got assaulted by a swan. I hadn't let go of a piece of bread fast enough. The creature rushed at me with the wings of a dragon, a neck of steel, and a beak that hit like a hammer. So when Matthew Bourne, in his version of Swan Lake, turned Petipa's demure elfin princesses into ferocious attack birds, I knew what he was talking about. Bare-chested male swans in feathered pants may be Bourne's most spectacular contribution to this fabulous 1995 Swan Lake, but they are not the sole reason to see this truly original and radical rethinking of the world's most popular ballet. By refocusing the story on the prince and that Queen Mom of his, Bourne at last came up with an answer to what has bothered many of us about the traditional tale: What's the matter with that dork of a prince who can't tell the black from the white swan? While the show is uproariously funny