Moviegoers who see the new Gerard Butler headlining film “Machine Gun Preacher,” based on the life of heroin-addict-turned-Christian-child-crusader Sam Childers, would understandably believe Hollywood exaggerated the story for entertainment purposes. But they’ll be surprised to know that the real life of Childers was too much for even Hollywood. Director Marc Forster – whose credits include “Finding Neverland,” “Quantum of Solace,” and “Monster’s Ball” – includes all the typical elements of an R-rated film: sex, drugs and violence. But screenwriter Jason Keller noted Thursday at the film’s Washington, D.C. screening that he couldn’t include some experiences in Childers’ earlier "bad-boy" life...