Make LenaPi usable on Android devices

- Add app icon
- prevend android device from shutting down cpu while playing music
- fix scaling bug
- fix energy saver for RasPi by reconnecting to music player
- minor refactorings and renaming

LenaPi/controllers/NavigationController.h

@@ -86,6 +86,7 @@ private slots:
      * @brief Either show subdirectories or music player depending on current directory type
      */
     void onNavigationRequest();
+    void startOrStopEnergySaverDependingOnPlayerState();
 };
 
 #endif // NAVIGATIONCONTROLLER_H