Winterthur’s new exhibit is touted as the behind-the-scenes story of the White House restoration in 1961-62. Winterthur Museum will be sprinkled with a bit of fairy dust from Camelot throughout the rest of the year. The estate on Saturday opened its new exhibit, “Jacqueline Kennedy and Henry Francis du Pont: From Winterthur to the White House,” touted as the behind-the-scenes …