Checkpoint game before sim, auto-revert on abort.

An alternative to
https://github.com/dcs-liberation/dcs_liberation/pull/2891 that I ended
up liking much better (I had assumed some part of the UI would fail or
at least look terrible with this approach, but it seems to work quite
well).

On by default now since it's far less frightening than the previous
thing.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2735.

game/sim/aircraftsimulation.py

@@ -69,12 +69,9 @@ class AircraftSimulation:
         for flight in self.iter_flights():
             flight.state.reinitialize(now)
 
-    def reset(self, events: GameUpdateEvents | None = None) -> None:
-        if events is None:
-            events = GameUpdateEvents()
+    def reset(self) -> None:
         for flight in self.iter_flights():
             flight.set_state(Uninitialized(flight, self.game.settings))
-            events.update_flight(flight)
         self.combats = []
 
     def iter_flights(self) -> Iterator[Flight]:

game/sim/gameloop.py

@@ -36,17 +36,10 @@ class GameLoop:
     def elapsed_time(self) -> timedelta:
         return self.sim.time - self.game.conditions.start_time
 
-    def reset(self) -> None:
-        self.pause()
-        self.events = GameUpdateEvents()
-        self.sim.reset(self.events)
-        self.send_update(rate_limit=False)
-        self.started = False
-        self.completed = False
-
     def start(self) -> None:
         if self.started:
             raise RuntimeError("Cannot start game loop because it has already started")
+        self.game.save_manager.save_pre_sim_checkpoint()
         self.started = True
         self.sim.begin_simulation()
 

game/sim/missionsimulation.py

@@ -33,11 +33,6 @@ class MissionSimulation:
         self.completed = False
         self.time = self.game.conditions.start_time
 
-    def reset(self, events: GameUpdateEvents) -> None:
-        self.completed = False
-        self.time = self.game.conditions.start_time
-        self.aircraft_simulation.reset(events)
-
     def begin_simulation(self) -> None:
         self.time = self.game.conditions.start_time
         self.aircraft_simulation.begin_simulation()