NEW YORK (Reuters) - Americans are carrying a lot of excess weight and desperately want to slim down. No, not their waistlines -- in the size of their homes. "Steeply deteriorating." "Hard landing." "Kaput." These are some of the terms used by analysts to describe the slowing of the U.S. housing market. And with the glory days of home-price appreciation now over, some homeowners are declaring, "Downsize Me!"A huge gap between the supply of homes for sale and demand for housing means prices are leveling off -- and could tumble. David Horwitz and his wife, Diane, are the type of...