object: added onDestroying signal

server/src/core/object.cpp

@@ -45,6 +45,7 @@ void Object::destroy()
   {
     m_dying = true;
     destroying();
+    onDestroying(*this);
   }
 }
 

server/src/core/object.hpp

@@ -63,6 +63,7 @@ class Object : public std::enable_shared_from_this<Object>
     virtual void worldEvent(WorldState state, WorldEvent event);
 
   public:
+    boost::signals2::signal<void (Object&)> onDestroying;
     boost::signals2::signal<void (BaseProperty&)> propertyChanged;
     boost::signals2::signal<void (AbstractAttribute&)> attributeChanged;