Add RemoveAllListeners function for future addons

pcbnew/board.cpp

@@ -1966,6 +1966,12 @@ void BOARD::RemoveListener( BOARD_LISTENER* aListener )
 }
 
 
+void BOARD::RemoveAllListeners()
+{
+    m_listeners.clear();
+}
+
+
 void BOARD::OnItemChanged( BOARD_ITEM* aItem )
 {
     InvokeListeners( &BOARD_LISTENER::OnBoardItemChanged, *this, aItem );

pcbnew/board.h

@@ -1081,6 +1081,11 @@ public:
      */
     void RemoveListener( BOARD_LISTENER* aListener );
 
+    /**
+     * Remove all listeners
+     */
+    void RemoveAllListeners();
+
     /**
       * Notify the board and its listeners that an item on the board has
       * been modified in some way.

pcbnew/pcb_edit_frame.cpp

@@ -448,7 +448,7 @@ PCB_EDIT_FRAME::~PCB_EDIT_FRAME()
         m_toolManager->ShutdownAllTools();
 
     if( GetBoard() )
-        GetBoard()->RemoveListener( m_appearancePanel );
+        GetBoard()->RemoveAllListeners();
 
     delete m_selectionFilterPanel;
     delete m_appearancePanel;