ROME/BEIRUT (Reuters) - Syria's civil war has ravaged vital infrastructure and halved output of staple crops, the United Nations said on Wednesday, as a 22-month conflict hardened by sectarian rivalry showed no sign of abating. What began as a peaceful protest movement against President Bashar al-Assad has killed more than 60,000 people, devastated the economy and left 2.5 million people hungry. Prospects of a negotiated peace have receded as the war becomes more overtly sectarian, making Western powers more wary of supporting the largely Sunni Muslim - and increasingly radicalized - ...