Clear transports when disbanding convoys.

Also changes when we clear the convoys. Because we plan when transfers
are added (to plan UI orders immediately) we were planning convoys when
delivering units, then clearing the convoys, then planning them again.

Aside from the wasted effort, when we cleared the convoys we forgot to
tell the transfer that they no longer had transport, so when replanning
they did not get a new convoy.

game/game.py

@@ -291,7 +291,6 @@ class Game:
 
         # Needs to happen *before* planning transfers so we don't cancel the
         self.reset_ato()
-
         for control_point in self.theater.controlpoints:
             control_point.process_turn(self)