A convincing bottom-line beat and notable strategic change excited investors about the company's future.One of the winners on the stock exchange Thursday was Southwest Airlines (LUV 5.52%). The ever-scrappy carrier's share price had plenty of lift, with investors sending it up by more than 5% following an estimate-beating quarterly earnings report.An announcement of certain changes in operating strategy also helped. That 5%-plus gain contrasted with the S&P 500 index, which slumped to close 0.5% lower on th ...