“The thing is,” Mark Knopfler says of his craft, “if you’ve energized somebody . . . or you’ve sensitized somebody, you’ve made a difference.” In a body of work spanning nearly five decades, the Sultan of Song has continued to do just that, sensitizing listeners to the drama of the oft overlooked. “It’s a creative act,” he says, “you drop it in the well. The ripples go out and you never know what’s going to come back.” What’s come back in his case is a resounding “no” to the idea that “it’s all been done before.”