Dark Mode & Stream Overlay [macOS] (#315)

* dark mode & stream overlay

* removed all redundant imports

* update for the new xcode version with fixes for the new 'implicitly retains self warning'

* reworked the overlay view

* cleaning up unused variables

* small corrections

Moonlight macOS/Network/NetworkTraffic.h

@@ -0,0 +1,15 @@
+//
+//  NetworkTraffic.h
+//  Moonlight macOS
+//
+//  Created by Felix Kratz on 28.03.18.
+//  Copyright © 2018 Felix Kratz. All rights reserved.
+//
+
+#ifndef NetworkTraffic_h
+#define NetworkTraffic_h
+
+unsigned long getBytesDown(void);
+unsigned long getBytesUp(void);
+
+#endif /* NetworkTraffic_h */