Fix kicking of NPCs via "kick user" console command.

Needed to hook up the Close() function in the NPCAvatar IClientAPI implementation, which [unfortunately] is still needed

OpenSim/Region/OptionalModules/World/NPC/NPCAvatar.cs

@@ -842,6 +842,8 @@ namespace OpenSim.Region.OptionalModules.World.NPC
 
         public void Close()
         {
+            // Remove ourselves from the scene
+            m_scene.RemoveClient(AgentId, false);            
         }
 
         public void Start()