Unit composition is defined by the doctrine. The most understaffed CP
will now get the most underrepresented unit type. Previously a random
understaffed CP would get a random unit type.
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/1057.
Still a work in progress (the missions don't actually perform their task, just orbit). Currently:
* AEW&C aircraft can be bought.
* AEW&C missions can be planned at any control point and at front lines.
* AEW&C will return after 4H or Bingo.
If the captured base has no connection to other friendly objectives (the
base was encircled) then the enemy equipment will be captured and sold.
Otherwise the units will retreat toward connected bases.
Partial fix for https://github.com/Khopa/dcs_liberation/issues/693.
Still need to fix this for air units.
