Fantastical is one of the best and most powerful calendar apps on the market. Since it first launched in 2011, it has been both nicer to look at and easier to use than your average calendaring tool. I’ve been a user for years, and every time I switch away, I come back for the design, the natural-language processing that lets you create events just by typing “Lunch with Arthur 12:30 Friday at Panera,” and the integrations with to-do list apps. It’s an expensive app, at $57 a year or…