TORONTO (Reuters) - One sentence, a political comment as bombs rained down on Baghdad in 2003, changed the careers and the fan base of Texas-based Dixie Chicks, but not their spirit or their tune. "In the past, I think we thought we had a purpose, to entertain (the audience)," said lead singer Natalie Maines, whose 2003 comments criticizing U.S. president George W. Bush made the band a pariah in the country music world. "Now you feel like they feel like they have a purpose, in supporting free speech and supporting us, so it's amazing. And it's definitely a new audience."...