GLOBAL MARKETS-Russia turmoil sparks flight to safety

* Core bond yields, shares fall in European trading session* U.S. Federal Reserve statement due later* Short-lived rouble rebound after Finance Ministry sells FX* Greece vote also in focusBy Lionel LaurentLONDON, Dec 17 (Reuters) - Fears of a full-blown crisis in Russia and oil&aposs continued slide pushed investors to seek safety on Wednesday, buying core bonds yields and selling stocks while the