At least 18 people were killed Sunday when a double bomb attack hit a Catholic church on a southern Philippine island that is a stronghold of Islamist militants, the military said, days after voters backed expanded Muslim self-rule in the region.In an attack claimed by the Islamic State (IS) group, a powerful first blast shattered pews, broke windows and left bodies strewn inside the cathedral in the Catholic-majority nation's restive south as mass was being celebrated.Moments later a se