Plan waypoint TOTs.

Also fixes the CAP racetracks so the AI actually stays on station.

Waypoint TOT assignment happens at mission generation time for the
sake of the UI. It's a bit messy since we have the late-initialized
field in FlightWaypoint, but on the other hand we don't have to reset
every extant waypoint whenever the player adjusts the mission's TOT.

If we want to clean this up a bit more, we could have two distinct
types for waypoints: one for the planning stage and one with the
resolved TOTs. We already do some thing like this with Flight vs
FlightData.

Future improvements:

* Estimate the group's ground speed so we don't need such wide margins
  of error.
* Delay takeoff to cut loiter fuel cost.
* Plan mission TOT based on the aircraft in the package and their
  travel times to the objective.
* Tune target area time prediction. Flights often don't need to travel
  all the way to the target point, and probably won't be doing it
  slowly, so the current planning causes a lot of extra time spent in
  enemy territory.
* Per-flight TOT offsets from the package to allow a sweep to arrive
  before the rest, etc.

gen/ato.py

@@ -8,14 +8,15 @@ example, the package to strike an enemy airfield may contain an escort flight,
 a SEAD flight, and the strike aircraft themselves. CAP packages may contain only
 the single CAP flight.
 """
+import logging
 from collections import defaultdict
 from dataclasses import dataclass, field
-import logging
-from typing import Dict, Iterator, List, Optional
+from typing import Dict, List, Optional
 
 from dcs.mapping import Point
-from .flights.flight import Flight, FlightType
+
 from theater.missiontarget import MissionTarget
+from .flights.flight import Flight, FlightType
 
 
 @dataclass(frozen=True)
@@ -29,6 +30,14 @@ class Task:
     location: str
 
 
+@dataclass(frozen=True)
+class PackageWaypoints:
+    join: Point
+    ingress: Point
+    egress: Point
+    split: Point
+
+
 @dataclass
 class Package:
     """A mission package."""
@@ -42,10 +51,10 @@ class Package:
 
     delay: int = field(default=0)
 
-    join_point: Optional[Point] = field(default=None, init=False, hash=False)
-    split_point: Optional[Point] = field(default=None, init=False, hash=False)
-    ingress_point: Optional[Point] = field(default=None, init=False, hash=False)
-    egress_point: Optional[Point] = field(default=None, init=False, hash=False)
+    #: Desired TOT measured in seconds from mission start.
+    time_over_target: Optional[int] = field(default=None)
+
+    waypoints: Optional[PackageWaypoints] = field(default=None)
 
     def add_flight(self, flight: Flight) -> None:
         """Adds a flight to the package."""
@@ -55,8 +64,7 @@ class Package:
         """Removes a flight from the package."""
         self.flights.remove(flight)
         if not self.flights:
-            self.ingress_point = None
-            self.egress_point = None
+            self.waypoints = None
 
     @property
     def primary_task(self) -> Optional[FlightType]: