MAHAMAT RAMADANE REBEL forces have set their sights on Chad's capital following the battlefield death of President Idriss Deby, a move that threatens to bring even more turmoil to a country vital to international efforts to combat Islamist militants in Africa. A spokesman for the Libyan-based rebel group, known as the Front for Change and Concord in Chad (FACT), said their aim was to bring democracy to the country after years of authoritarian rule by Deby. Rebel forces, who poured over the vast country's northern border last weekend, were now in Kanem region about 200-300 km (125-190 miles) north of…