GLOBAL MARKETS-Gold slumps, shares give back some of week's gains

* World share indexes steady at five-year high, dollar inches off lows * Gold prices fall, Wall St edges down; both on track for strong week * Euro near 7-1/2-month high vs dlr but traders cautious ahead of German vote * Indian markets roiled by surprise rate hike by central bank By Ryan Vlastelica NEW YORK, Sept 20 (Reuters) - Gold prices and stocks on major markets gave back some gains on Friday, after soaring earlier this week in the wake of the Federal Reserve's unexpec