IT almost seems like a gag worthy of “Borat”: A smooth-talking rookie senator with an exotic name passes himself off as the incumbent American president to credulous foreigners. But to dismiss Barack Obama’s magical mystery tour through old Europe and two war zones as a media-made fairy tale would be to underestimate the ingenious politics of the moment. History was on the march well before Mr. Obama boarded his plane, and his trip was perfectly timed to reap the whirlwind. CONTINUE . . .