Implemented minimum fixed-width menu

- Menus take the size of their title (or MIN_MENU_WIDTH if this is
  larger). Minimum size avoids tiny menus in case the feed title is too
  short
- Avoids menu resizing issues when expand submenus
- Feed labels automatically truncate
- Added item titles to tooltips to ensure they are visible even if the
  item title is truncated
Remove status icon from FeedDisplayMenuItem