CARDIFF, Wales (AP) - Even at 50, the queen of pop just can't stop courting controversy. As Madonna kicked off her international "Sticky and Sweet" tour Saturday night, she took a none-too subtle swipe at the presumptive Republican nominee for U.S. president. Amid a four-act show at Cardiff's packed Millennium Stadium, a video interlude carried images of destruction, global warming, Nazi dictator Adolf Hitler, Zimbabwe's authoritarian President Robert Mugabe - and U.S. Senator John McCain. Another sequence, shown later, pictured slain Beatle John Lennon, followed by climate activist Al Gore, Mahatma Gandhi and finally McCain's Democratic rival Barack Obama. The...