Balloons and Early Zeppelins

[McClainJ]

Description :

Issues regarding early observation balloons and early zeppelins.
They are so close to working, they just need an hour or two of love.

Branch :

Main

Issue List :

Balloons lack any assignable missions.

Zeppelins lack any assignable missions.
They also seem a little expensive, compared to early air-frames from the little research I did.
But that is just a suggestion.

The lack of missions causes any air-wings made from these craft to stop working.
Aircraft can be assigned, but the air-wing will fail to register and will not be removable,
assignable, or alterable.

An additional bug that seems unrelated to the mission assignments: Balloon air-wings and zeppelin air wings are unable to perform pilot exercises.

Recommended fixes:
Add assignable missions to the equipment definitions. Should fix all but the pilot exercises problem. I don't have any idea how to fix the pilot exercises issue.

Suggested alterations:
Reduce the production cost of the non-early zeppelins by 20-25%.
Reduce the production cost of the early zeppelins by 10-15%.