AFP: BP revealed Tuesday that the disaster in the Gulf of Mexico had cost it almost a billion dollars, sparking a 13-percent plunge in its shares after the latest attempt to fix the leaking well failed. At its lowest point, the British energy giant’s share price dropped nearly 17 percent on the day, but it recovered slightly to close at 430 pence, down 13.1 percent. The sell-off wiped more than 12 billion pounds (14.4 billion euros, 17.6 billion dollars) off its market value — its …