GLOBAL MARKETS-Brent hits four-year low after OPEC, dollar gains

* Brent crude rebounds after OPEC, but U.S. crude falls further* Falling energy shares weigh on global equities, Wall St rises* Dollar mostly strengthens on OPEC decision, bond yields fall(Adds U.S. market open, byline, dateline; previous LONDON)By Herbert LashNEW YORK, Nov 28 (Reuters) - Brent crude touched fresh four-year lows on Friday, knocking down both energy-related shares and currencies af