Allow NGW to be called from anywhere.

Any real end game dialog needs a "new game" button. If only the main
window can usefully call the NGW we'd have to plumb that object through
and call into it from that dialog, which is gross. Just make it easier
to call the wizard.

https://github.com/dcs-liberation/dcs_liberation/issues/978

qt_ui/windows/GameUpdateSignal.py

@@ -16,6 +16,7 @@ class GameUpdateSignal(QObject):
     debriefingReceived = Signal(Debriefing)
 
     game_loaded = Signal(Game)
+    game_generated = Signal(Game)
 
     def __init__(self):
         super(GameUpdateSignal, self).__init__()