Was it Hemingway or Fitzgerald who first used the phrase “Kill Your Darlings,” about the ruthless process of winnowing down, editing one’s writing? I always heard Hemingway. Daniel Radcliffe plays the Beat Poet Allen Ginsburg in this recreation of his formative college years. Ben Foster, Michael C. Hall, Elizabeth Olsen, Jack Huston as Kerouac, and as the academics, the great John Cullum and David Rasche. This one opens Oct. 18.