PARIS (Reuters) - Credit Agricole on Wednesday posted its biggest full-year loss since it went public 11 years ago, hit by unexpected costs from exiting Greece, weaker revenues and hefty asset writedowns. Investors warmed to the French bank's promise of a turnaround in 2013 and a pledge to cut 650 million euros from costs by 2016 through savings on back-office technology, equipment and real-estate. But it will pay no dividend after posting a net 2012 loss of 6.5 billion euros ($8.7 billion), hit by a surprise 838 million euro tax demand linked to the sale of Greek unit Emporiki. ...