* frontend to save states - menu items, maybe an extra pane
* improve level selection window (sorting, filtering)
* refactoring
    improve streak calculation
    ...
* display statistics: highscores should be displayed at the end of each game,
  listing the current position (#123 out of 323 played), # of game completed,
  # of games incomplete, average time, current time. the score window should
  display all scores instead of just the top 10
* color nonograms
* graphics themes (KGameThemeSelector)
