Fix highscore saving

* **Prevent saving of 0 highscore to database at startup**

ScoreArea.reset() is called on startup causing saving 0 highscore to database

* **connect slider.valueChanged to newGameRequest after component completed**

slider.valueChanged will called even *before* component is completed and the slider is not moved. This will cause newGameRequest called twice (one when slider valueChanged, one when component completed)