GLOBAL MARKETS-Stocks edge up as U.S. yields, dollar ease

(Recasts, adds Wall St open, background; changes byline and dateline, previous LONDON) * Wall Street shrugs off discouraging data * Dollar dips after Fed minutes defer rate hike bets * Oil tops $66 By Michael Connor NEW YORK, May 21 (Reuters) - Equities markets inched ahead on Thursday, with investors brushing aside mixed economic data in Europe and the United States, while the dollar slipped after a three-day rally and U.S. Treasury yields declined. Oil prices rose,