Add arrival/divert airfield selection.

Breaks save compat because it adds new fields to `Flight` that have no
constant default. Removing all of our other save compat at the same
time.

Note that player flights with a divert point will have a nav point for
their actual landing point. This is because we place the divert point
last, and DCS won't let us have a land point anywhere but the final
waypoint. It would allow a LandingReFuAr point, but they're only
generated for player flights anyway so it doesn't really matter.

Fixes https://github.com/Khopa/dcs_liberation/issues/342

qt_ui/widgets/combos/QArrivalAirfieldSelector.py

@@ -0,0 +1,47 @@
+"""Combo box for selecting a departure airfield."""
+from typing import Iterable
+
+from PySide2.QtWidgets import QComboBox
+from dcs.planes import PlaneType
+
+from game import db
+from game.theater.controlpoint import ControlPoint
+
+
+class QArrivalAirfieldSelector(QComboBox):
+    """A combo box for selecting a flight's arrival or divert airfield.
+
+    The combo box will automatically be populated with all airfields the given
+    aircraft type is able to land at.
+    """
+
+    def __init__(self, destinations: Iterable[ControlPoint],
+                 aircraft: PlaneType, optional_text: str) -> None:
+        super().__init__()
+        self.destinations = list(destinations)
+        self.aircraft = aircraft
+        self.optional_text = optional_text
+        self.rebuild_selector()
+        self.setCurrentIndex(0)
+
+    def change_aircraft(self, aircraft: PlaneType) -> None:
+        if self.aircraft == aircraft:
+            return
+        self.aircraft = aircraft
+        self.rebuild_selector()
+
+    def valid_destination(self, destination: ControlPoint) -> bool:
+        if destination.is_carrier and self.aircraft not in db.CARRIER_CAPABLE:
+            return False
+        if destination.is_lha and self.aircraft not in db.LHA_CAPABLE:
+            return False
+        return True
+
+    def rebuild_selector(self) -> None:
+        self.clear()
+        for destination in self.destinations:
+            if self.valid_destination(destination):
+                self.addItem(destination.name, destination)
+        self.model().sort(0)
+        self.insertItem(0, self.optional_text, None)
+        self.update()

qt_ui/widgets/map/QLiberationMap.py

@@ -373,6 +373,10 @@ class QLiberationMap(QGraphicsView):
             FlightWaypointType.TARGET_SHIP,
         )
         for idx, point in enumerate(flight.flight_plan.waypoints[1:]):
+            if point.waypoint_type == FlightWaypointType.DIVERT:
+                # Don't clutter the map showing divert points.
+                continue
+
             new_pos = self._transform_point(Point(point.x, point.y))
             self.draw_flight_path(scene, prev_pos, new_pos, is_player,
                                   selected)
@@ -386,7 +390,6 @@ class QLiberationMap(QGraphicsView):
                 self.draw_waypoint_info(scene, idx + 1, point, new_pos,
                                         flight.flight_plan)
             prev_pos = tuple(new_pos)
-        self.draw_flight_path(scene, prev_pos, pos, is_player, selected)
 
     def draw_waypoint(self, scene: QGraphicsScene, position: Tuple[int, int],
                       player: bool, selected: bool) -> None: