Simplify/clarify avatar settings
Show Avatars handling isn't very clear on what actually happens and can leave someone confused about what affects what.
Avatar handling should probably be moved into it's own section, perhaps under an
Appearance pane as part of reorganizing the client settings.
Show Avatars controls
Show Avatars in Messages and IRCv3 avatar fetching functionality. Avatars elsewhere are always shown, but could use settings to manage that.
Avatar fetching section and a
Display section for where they're actually shown, with the notion that if all display options are disabled (if possible), nothing's fetched, either.