- Add category metadata in every extension
- Show this category in the extension list gui
- Add "mandatory_in" and "disable-in" configuration for an extension
- Add Ubuntu unity check to enable/disable unity specific extensions
- Move "gpodder.win32" and "gpodder.osx" setting to the "gpodder.ui" namespace to be able to use it in the extensions category settings
- Only show metadata information in the right-click dialog of an extension