Core/Game: Include cleanup part 5

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

src/server/scripts/Events/childrens_week.cpp

@@ -16,6 +16,7 @@
  */
 
 #include "ScriptMgr.h"
+#include "MotionMaster.h"
 #include "ObjectAccessor.h"
 #include "Player.h"
 #include "ScriptedCreature.h"