Fix for non-working DELETE key in Playlist on Win32

For some unknown reason, wxwidgets 2.6.3 always return WXK_NUMPAD_DELETE
even in case normal Delete key was pressed

Please consider backporting just for Win32 binaries.

modules/gui/wxwidgets/dialogs/playlist.cpp

@@ -1146,7 +1146,7 @@ void Playlist::OnKeyDown( wxTreeEvent& event )
 {
     long keycode = event.GetKeyCode();
     /* Delete selected items */
-    if( keycode == WXK_BACK || keycode == WXK_DELETE )
+    if( keycode == WXK_BACK || keycode == WXK_DELETE || keycode == WXK_NUMPAD_DELETE )
     {
         /* We send a dummy event */
         OnDeleteSelection( event );