Improvements to user profiles:

- Set a minimum width on the profile window (avatar size + margins)
- Made avatar editing a separate button, so you can zoom in on your own avatars
- Added hover text to avatar/displayname change buttons, which clarify where they will apply for global/room-specific profiles
- Added display of room name for room-specific profiles, with hover text that explains what that means.
- Added way to open global profile for users from their room-specific profiles (globe button next to room name)