It’s a day of James Cagney movies on TCM –and while a handful of Cagney films could have qualified for presentation on tonight’s installment of “The Essentials,” the prime-time showcase honor is given to one of Cagney’s best and most influential: 1949’s White Heat. This was a gangster movie from Cagney’s second, later wave of moviemaking, but it’s no less classic. What a character. What a portrayal. And what an ending. When James Cameron won his Oscar for directing Titanic and screamed “King of the world,” he was quoting the end of this movie – incorrectly, but alluding nonetheless to one of cinema’s great concluding scenes.