LONDON (Reuters) - Hot on the heels of her Super Bowl half-time performance, U.S. singer Beyonce has announced a world tour kicking off in Belgrade on April 15 and wrapping up in New York on August 3. The tour, which so far includes 19 European cities and more than 20 in North America, is part of the 31-year-old's carefully crafted comeback since giving birth to her first child with rapper and husband Jay-Z in January, 2012. Some online media reports said a second wave of performances would be announced for Latin America and Asia, but there were no such details on her official website. ...