Core/Game: Include cleanup part 5

* ObjectMgr.h
* Player.h
* Unit.h
* G3D should no longer propagate everywhere from Spline/MotionMaster

src/server/game/Scripting/ScriptMgr.cpp

@@ -26,6 +26,7 @@
 #include "Errors.h"
 #include "GameObject.h"
 #include "GossipDef.h"
+#include "Item.h"
 #include "LFGScripts.h"
 #include "Log.h"
 #include "Map.h"