NEW YORK (Reuters) - Oil fell nearly 3 percent on Monday, echoing the weakness in global stock markets as the focus returned to concerns about growth in demand and crude prices erased some of the gains made last week on an OPEC-led decision to cut output.A gauge of global equities stumbled on Monday, as losses in Europe and Asia extended to Wall Street on new signs the U.S.-China trade war was impacting world economic growth, but rebounded from an initial drop as Apple Inc shares recovered. The..