Reuters DAKAR? France urged African nations on Monday to step up cross-border cooperation to tackle security challenges from Islamist groups in southern Libya to Boko Haram attacks in Nigeria, as it seeks to scale back its military commitments on the continent. Amid budgetary pressures at home, France is looking to reduce security commitments in Africa. It is scaling back the 2,000 troops it deployed a year ago to curb Christian-Muslim violence in...