Fix order of initialization of C4Game/C4GraphicsSystem.

Game.GraphicsSystem could be constructed after Game, but was accessed in C4Game::Default.

src/C4Globals.cpp

@@ -22,6 +22,7 @@
 #include "C4Console.h"
 #include <C4DefList.h>
 #include "C4FullScreen.h"
+#include "C4GraphicsSystem.h"
 #include "C4Game.h"
 #include "C4GameObjects.h"
 #include "C4MouseControl.h"
@@ -44,5 +45,8 @@ C4FullScreen   FullScreen;
 C4MouseControl MouseControl;
 C4GameObjects  Objects;
 C4DefList      Definitions;
+// make sure C4Game reference members are initialized before Game because otherwise they're acccessed in C4Game::Default before initialization
+C4GraphicsSystem GraphicsSystem;
 C4Game         Game;
 C4Network2     Network;
+

src/game/C4GraphicsSystem.cpp

@@ -459,4 +459,3 @@ bool C4GraphicsSystem::ToggleShowHelp()
 	return true;
 }
 
-C4GraphicsSystem GraphicsSystem;