Fix custom waypoints.

Like with deleting waypoints, these will degrade the flight plan to the
2.1 behavior.

Ascend/descend points aren't in use any more, so I removed those.

game/theater/theatergroundobject.py

@@ -101,6 +101,10 @@ class TheaterGroundObject(MissionTarget):
         """The name of the unit group."""
         return f"{self.category}|{self.group_id}"
 
+    @property
+    def waypoint_name(self) -> str:
+        return f"[{self.name}] {self.category}"
+
     def __str__(self) -> str:
         return NAME_BY_CATEGORY[self.category]
 
@@ -155,6 +159,10 @@ class BuildingGroundObject(TheaterGroundObject):
         """The name of the unit group."""
         return f"{self.category}|{self.group_id}|{self.object_id}"
 
+    @property
+    def waypoint_name(self) -> str:
+        return f"{super().waypoint_name} #{self.object_id}"
+
 
 class NavalGroundObject(TheaterGroundObject):
     def mission_types(self, for_player: bool) -> Iterator[FlightType]: