LONDON (Reuters) - Oil prices edged higher on Thursday ahead of an OPEC meeting where members are expected to agree on deeper output cuts in an effort to prop up prices and prevent a glut next year.Sources told Reuters that OPEC was seeking to increase production cuts by the group and its allies by Russia by more than 400,000 barrels per day (bpd) from their current level of 1.2 million bpd.The Organization of the Petroleum Exporting Countries meets on Thursday in Vienna followed by a meeting on..