GLOBAL MARKETS-Shares steady, dollar edges lower ahead of key U.S. events

(Updates prices, adds quotes) * Russia stocks tumble anew after new sanctions * Investors hesitant to make bets ahead of GDP, payrolls data * Fed expected to maintain dovish tone on Wednesday By Angela Moon NEW YORK, July 28 (Reuters) - World stock markets were little changed on Monday while the U.S. dollar edged lower against a basket of major currencies ahead of a ream of U.S. data and events this week. MSCI's All-World Index erased earlier losses to trade flat as majo