GLOBAL MARKETS-OPEC inaction sends Brent to four-year low, hits stocks

* Brent Crude rallies off 4 year low, but set for 15 pct Nov drop* FTSEurofirst falls, led lower by oil & gas stocks* Euro zone data shows inflation weak, Bund pinned at lows* Dollar gains against commodity currencies, euro and yenBy Alistair SmoutLONDON, Nov 28 (Reuters) - Brent crude fell to a fresh four-year low on Friday, sending oil-related shares and currencies lower, after OPEC decided to r