Just listening to Anny Densmore talk about singing will make you want to burst into song. And as far as she’s concerned, you should start now, even if you’re tone deaf and have no sense of rhythm. But if you’re musically challenged, she has a plan for that. She has a system. It’s called circle singing. Unsurprisingly, it involves circles of humans singing. The number of circles varies, depending on who shows up. “Circle singing…