This was also needed in other parts of the UI and is easier to implement
in the target class anyway.
Note that DEAD is now properly restricted to air defense targets.
Also added error boxes to the UI for when planning fails on an invalid
target.
`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.
Logging before we've made it to the logging setup was causing the root
logger to be permanently configured to the default (warning) log
level, so we weren't getting any info or debug logs any more.
Defer the campaign data load until it is needed rather than doing it
at import time. I've also cleaned up a bit so we only load each
campaign once, rather than re-loading the campaign to create the
theater again after the wizard is finished.
Mission planning has been completely redone. Missions are now planned
by right clicking the target area and choosing "New package".
A package can include multiple flights for the same objective. Right
now the automatic flight planner is only fragging single-flight
packages in the same manner that it used to, but that can be improved
now.
The air tasking order (ATO) is now the left bar of the main UI. This
shows every fragged package, and the flights in the selected package.
The info bar that was previously on the left is now a smaller bar at
the bottom of the screen. The old "Mission Planning" button is now
just the "Take Off" button.
The flight plan display no longer shows enemy flight plans. That could
be re-added if needed, probably with a difficulty/cheat option.
Aircraft inventories have been disassociated from the Planner class.
Aircraft inventories are now stored globally in the Game object.
Save games made prior to this update will not be compatible do to the
changes in how aircraft inventories and planned flights are stored.
