Add --force flag to "kick user" console command to allow bypassing of recent race condition checks.

This is to allow a second attempt to remove an avatar even if "show connections" shows them as already inactive (i.e. close has already been attempted once).
You should only attempt --force if a normal kick fails.
This is partly for diagnostics as we have seen some connections occasionally remain on lbsa plaza even if they are registered as inactive.
This is not a permanent solution and may not work anyway - the ultimate solution is to stop this problem from happening in the first place.

OpenSim/Framework/IClientAPI.cs

@@ -1033,7 +1033,21 @@ namespace OpenSim.Framework
 
         void InPacket(object NewPack);
         void ProcessInPacket(Packet NewPack);
+
+        /// <summary>
+        /// Close this client
+        /// </summary>
         void Close();
+
+        /// <summary>
+        /// Close this client
+        /// </summary>
+        /// <param name='force'>
+        /// If true, attempts the close without checking active status.  You do not want to try this except as a last
+        /// ditch attempt where Active == false but the ScenePresence still exists.
+        /// </param>
+        void Close(bool force);
+
         void Kick(string message);
         
         /// <summary>