Dollar firms before payrolls, Greece unease simmers

By Marc Jones LONDON (Reuters) - The dollar was near a three-week high on Thursday and world stock markets had a delicate feel, as the implication of U.S. jobs data later for a possible Fed rate hike added to Europe's uncertainty over Greece. Europe's main bourses in London , Frankfurt and Paris and Milan opened largely flat having rallied on Wednesday but the mood remained skittish after hopes of a last minute aid deal between Athens and the euro zone evaporated. A defiant Prime Minis