REUTERS/Caren Firouz/Files Pakistan's Prime Minister Nawaz Sharif will be questioned on Thursday by investigators probing how his family obtained its vast wealth, the first time a sitting Pakistani premier has appeared before any investigative agency. Sharif's office on Monday confirmed the prime minister had received a summons by the Joint Investigation Team (JIT), set up by the Supreme Court to investigate corruption claims that surfaced following the Panama Papers leak. It said he would be...