Conservatives call for truce in EU campaign

By Elizabeth Piper LONDON (Reuters) - Senior ministers called on Sunday for a truce in a heated debate on Britain's membership of the European Union, saying the ruling Conservative Party must be civil if it wants to stay in power. The party is deeply split over whether Britain should vote to stay in the EU at a referendum on June 23, and several allies of Prime Minister David Cameron, who supports EU membership, are campaigning to leave the 28-member bloc. Some lawmakers have criticised Cameron