GLOBAL MARKETS-Dollar gain hits commodities; stocks drop for quarter

* Dip in euro zone inflation knocks euro down, lifts dollar * Global equity markets head for worst quarter in two years * Dollar strength drags gold, oil lower (Adds close of U.S. markets) By Chuck Mikolajczak NEW YORK, Sept 30 (Reuters) - The dollar advanced on Tuesday after weak euro zone inflation data for September heightened expectations of stimulus from the European Central Bank, while world stock markets recorded their largest quarterly drop in more than two years. T