GLOBAL MARKETS-Equities extend rally; oil rebounds, helping rouble rise

(Updates prices to close, adds comment) * U.S. stocks post best three days since 2011 * Rouble bounces 5 percent; oil tops $62 a barrel By David Gaffen NEW YORK, Dec 19 (Reuters) - Equity markets worldwide extended the week's rally on Friday and oil prices rebounded from recent lows, as investors closed out the last full week of trading in 2014 on an upbeat note. Wall Street rose, and the S&P 500 came within a few points of its closing record high. The index has gained 5 per