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/MouseEventSpy.cpp

@@ -12,7 +12,7 @@ void MouseEventSpy::init()
 MouseEventSpy* MouseEventSpy::instance()
 {
     static MouseEventSpy* inst;
-    if (inst == nullptr)
+    if (!inst)
     {
         inst = new MouseEventSpy();
         QGuiApplication* app = qGuiApp;