New notifications menu for Discourse

Discourse upstream has implemented a new notifications / personal menu — the one you get when you click on your avatar at the very top right. I’ve enabled this, because as far as I can see, it is strictly better. Different types of notifications (for example, for new replies to a topic you are watching vs. someone adding a :heart: to one of your posts) are broken into different sections, and the layout is a little better. Let me know if you experience any problems!