Half-baked Barbara By John McCaslin October 7, 2005 It's not easy being the master of ceremonies for a roast when half of the roasters don't show up. Ask political commentator Mark Shields, who found himself in that uncomfortable position Wednesday evening as the Spina Bifida Association attempted to put TV personality Barbara Walters in the "hot seat" at the Hyatt Regency Washington. "This is more like a bake-off," a visibly embarrassed Mrs. Walters said after the roasting, expressing disappointment that Sen. Hillary Rodham Clinton of New York and fellow roaster Sen. Mary L. Landrieu of Louisiana were no-shows. As it...