made object state polymorphic

components/esm/objectstate.cpp

@@ -46,4 +46,6 @@ void ESM::ObjectState::save (ESMWriter &esm, bool inInventory) const
         esm.writeHNT ("POS_", mPosition, 24);
         esm.writeHNT ("LROT", mLocalRotation, 12);
     }
-}
+}
+
+ESM::ObjectState::~ObjectState() {}

components/esm/objectstate.hpp

@@ -26,8 +26,10 @@ namespace ESM
         ESM::Position mPosition;
         float mLocalRotation[3];
 
-        void load (ESMReader &esm);
-        void save (ESMWriter &esm, bool inInventory = false) const;
+        virtual void load (ESMReader &esm);
+        virtual void save (ESMWriter &esm, bool inInventory = false) const;
+
+        virtual ~ObjectState();
     };
 }