* Oil prices near 4-year low as OPEC output cut hopes fade* European shares buoyed by ECB bond-buying hopes* Asian shares edge up, helped by stimulus around the world* Dollar slips after underwhelming U.S. dataBy Marc JonesLONDON, Nov 27 (Reuters) - Fading hopes of a meaningful cut in production at Thursday&aposs OPEC meeting sent oil prices tumbling to a four-year low as Thanksgiving in the Unite