Commit squashed refactoring branch

- introduce settings dialog
- general settings for general / proxy settings
- standalone proxy settings dialog removed
- standalone status dialog removed
- moved status dialog into settings dialog
- radically cut down links in context menu
- add help link to context menu

This needs more cleanup and testing. Known issues:

- When the wizard is called while the settings dialog
  is open, it will not show old information (see FIXME)
- Some settings are not implemented yet (greyed out)
- The counter in the FileItemDialog is not correct the
  first time around.

Based on the discussion done with Jan and Klaas during the
Nuenberg workshop.