DALLAS - If you're planning a big vacation trip this summer, move over. You're going to have lots of company. By air or car, traveller numbers are expected to rise over last year thanks to a decent eco**my and stable gasoline prices. U.S. airlines expect to carry 234 million passengers from June 1 through Aug. 31, up from the summer record of 225 million a year ago, according to the trade group Airlines for America. While fares are edging up overall, ...