Core/Game: Include cleanup part 5

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

src/server/scripts/Commands/cs_instance.cpp

@@ -33,6 +33,7 @@ EndScriptData */
 #include "ObjectMgr.h"
 #include "Player.h"
 #include "RBAC.h"
+#include "WorldSession.h"
 
 class instance_commandscript : public CommandScript
 {