Not a question was asked, not a word was spoken about the old rape case, as Nate Parker's The Birth of a Nation got a warm welcome — and a respectfully soft landing — at the Toronto International Film Festival on Friday night. "What did Nat Turner's story mean to you?" Cameron Bailey, the festival's artistic director, asked Parker, the director and star of the film, in a delicately choreographed Q&A session that followed the first festival screening at the Winter Garden…