Cameron heads for 'now or never' talks to keep Britain in EU

By Elizabeth Piper and Alastair Macdonald BRUSSELS (Reuters) - Prime Minister David Cameron will hold "now or never" talks on Thursday to keep Britain in the European Union, with the bloc's leaders voicing optimism that agreement can be reached on a new membership deal. In the latest draft agreement sent to EU leaders overnight and seen by Reuters, officials tried to overcome differences over the most contentious areas of Cameron's renegotiation - migration curbs and financial safeguards - but m