* src/main.c:

    - only read the preferences file once when using the application.
    - check if the directory name stored in the preferences still exists
      before trying to use it.
  * lib/screenshooter-actions.c: set home as the default folder for the
    file chooser, only use sd->screenshot_dir when we don't show the
    save dialog. This should be more transparent for the user.


(Old svn revision: 6370)