Hint tracking

[fenhl]

• [ ] Extend the text box parser to read gossip hints and store them in knowledge.
• [ ] Add a separate window (blocked on iced-rs/iced#27 with a possible workaround using multiple processes) or pane (requires programmatic resizing implemented in iced-rs/iced#1019, need to move iced to a git dependency again or wait for a release) displaying all known hints, with the option to enter new ones if not auto-tracking.