Nick Krewen Special To The Star “It ain’t gonna stop now!” a feisty Gordon Lightfoot declares at the conclusion of a 30-minute interview about the state of his six-decade-plus career. We’re sitting at a table at his record company headquarters north of the 401, and it’s obvious that at 81, the fire still rages in the Orillia-born troubadour’s belly. He’s not interested at slowing down in the slightest. Lightfoot, who resumes touring…