Previously the only difference between these was the objective type:
TARCAP was for front lines and BARCAP was for everything else.
Now BARCAP is for friendly areas and TARCAP is for enemy areas. The
practical difference between the two is that a TARCAP package is like
the old front line CAP in that it will adjust its patrol time to match
the package if it can, and it will also arrive two minutes ahead of the
rest of the package to clear the area if needed.
`FrontLine` is tightly coupled with `ConflictTheater`.
Moved into the same module to prevent circular imports.
Moved `ConflictTheater.frontline_data` from class var
to instance var to allow save games to have different
versions of frontlines.
Mission planning on a per-control point basis lacked the context it
needed to make good decisions, and the ability to make larger missions
that pulled aircraft from multiple airfields.
The per-CP planners have been replaced in favor of a global planner
per coalition. The planner generates a list of potential missions in
order of priority and then allocates aircraft to the proposed flights
until no missions remain.
Mission planning behavior has changed:
* CAP flights will now only be generated for airfields within a
predefined threat range of an enemy airfield.
* CAS, SEAD, and strike missions get escorts. Strike missions get a
SEAD flight.
* CAS, SEAD, and strike missions will not be planned unless
they have an escort available.
* Missions may originate from multiple airfields.
There's more to do:
* The range limitations imposed on the mission planner should take
aircraft range limitations into account.
* Air superiority aircraft like the F-15 should be preferred for CAP
over multi-role aircraft like the F/A-18 since otherwise we run the
risk of running out of ground attack capable aircraft even though
there are still unused aircraft.
* Mission priorities may need tuning.
* Target areas could be analyzed for potential threats, allowing
escort flights to be optional or omitted if there is no threat to
defend against. For example, late game a SEAD flight for a strike
mission probably is not necessary.
* SAM threat should be judged by how close the extent of the SAM's
range is to friendly locations, not the distance to the site itself.
An SA-10 30 nm away is more threatening than an SA-6 25 nm away.
* Much of the planning behavior should be factored out into the
coalition's doctrine.
But as-is this is an improvement over the existing behavior, so those
things can be follow ups.
The potential regression in behavior here is that we're no longer
planning multiple cycles of missions. Each objective will get one CAP.
I think this fits better with the turn cycle of the game, as a CAP
flight should be able to remain on station for the duration of the
turn (especially with refueling).
Note that this does break save compatibility as the old planner was a
part of the game object, and since that class is now gone it can't be
unpickled.
