It’s Saturday night in Montreal, and I’m determined not to slink back home until at least 10 pm. Montreal prides itself on being the fun and festive heart of Canada, and I want to take advantage. This city-on-an-island is having none of that, and celebrates about 110 festivals every year. So it’s a mathematical mystery how I’ve managed to arrive when there isn’t a single festival in sight. I’m too early for the world’s largest …