GLOBAL MARKETS-Stocks climb on Fed policy signals; oil slips again

(Updates with Wall Street rally, latest prices; changes dateline; previous LONDON) * Wall Street on track for second day of strong gains * Shares jump as Fed pledges to be patient on withdrawing stimulus * Oil down after brief short-covering gains By Michael Connor NEW YORK, Dec 18 (Reuters) - Global equities markets rallied on Thursday, with Wall Street up more than 1 percent for a second straight day on what investors viewed as a favorable result from the Federal Reserve's