Move unit delivery ownership out of the UI.

Breaks save compat, but we need to have this knowledge outside the UI so
we can know whether or not we can ferry aircraft to the airfield without
overflowing parking.

game/game.py

@@ -160,9 +160,6 @@ class Game:
     def _budget_player(self):
         self.budget += self.budget_reward_amount
 
-    def awacs_expense_commit(self):
-        self.budget -= AWACS_BUDGET_COST
-
     def units_delivery_event(self, to_cp: ControlPoint) -> UnitsDeliveryEvent:
         event = UnitsDeliveryEvent(attacker_name=self.player_name,
                                    defender_name=self.player_name,
@@ -172,10 +169,6 @@ class Game:
         self.events.append(event)
         return event
 
-    def units_delivery_remove(self, event: Event):
-        if event in self.events:
-            self.events.remove(event)
-
     def initiate_event(self, event: Event):
         #assert event in self.events
         logging.info("Generating {} (regular)".format(event))
@@ -242,6 +235,7 @@ class Game:
 
         self.aircraft_inventory.reset()
         for cp in self.theater.controlpoints:
+            cp.pending_unit_deliveries = self.units_delivery_event(cp)
             self.aircraft_inventory.set_from_control_point(cp)
 
         # Plan flights & combat for next turn