clear members list on server disconnect

gui/griffon-app/controllers/com/muwire/gui/ChatRoomController.groovy

@@ -271,4 +271,11 @@ class ChatRoomController {
         )
         model.core.eventBus.publish(event)
     }
+    
+    void serverDisconnected() {
+        runInsideUIAsync {
+            model.members.clear()
+            view.membersTable?.fireTableDataChanged()
+        }
+    }
 }

gui/griffon-app/controllers/com/muwire/gui/ChatServerController.groovy

@@ -18,6 +18,9 @@ class ChatServerController {
         switch(model.buttonText) {
             case "Disconnect" :
                 model.buttonText = "Connect"
+                mvcGroup.getChildrenGroups().each { k,v ->
+                    v.controller.serverDisconnected()
+                }
                 model.core.eventBus.publish(new UIDisconnectChatEvent(host : model.host))
                 break
             case "Connect" :