Fixed compilation without PCH enabled

please avoid to miss header files in your sources

src/game/Scripting/ScriptMgr.h

@@ -18,6 +18,7 @@
 #include "World.h"
 #include "Weather.h"
 #include "AchievementMgr.h"
+#include "DynamicObject.h"
 
 class AuctionHouseObject;
 class AuraScript;