Add methods to reset the ProjectList footer When going back from the move state ist must be possible to restore the old footer entry in the ProjectList. The footer may be overriden by the move state to select a project. In this case the old entry should be restored instead of showing a blank footer.

- Create empty databases from within getan.

- Create a 'Help-Widget' to give the user an information about all possible
  keys.

- reimplement RPN input for current getan implementation (28489e672e61)