RA Extra Shots for Fixed-Wing Aircraft

[ChthonVII]

There is a missing ammo check in AircraftClass::Mission_Hunt() that causes fixed-wing aircraft to fire an extra shot if they have the two-shooter property and their max ammo is an odd number. This applies to both MiG and Yak under the default rules.ini.

In my mod, I fixed the bug and then gave classes meeting those criteria +1 max ammo to preserve the classic balance. (See this commit.)