ef_verify: Reject invalid plane flag combinations

ef_verify: Reject invalid plane flag combinations

Any plane may have capabilities VTOL, helo, light.

Capability missile requires VTOL.

Anti-ballistic missiles have capabilities missile, SDI.

Anti-satellite missiles have capabilities missile, satellite.

Surface-to-air missiles have capabilities missile, intercept.

Anti-ship missiles have capabilities missile, marine, and may have
tactical.

Surface-to-surface missiles have capability missile, and may have
tactical.

Satellites have capability satellite, and may have spy, image.

Ordinary planes may have capabilities bomber, tactical, intercept,
cargo, spy, image, ASW, para, escort, mine, sweep.  Capability para
requires cargo; see para().

Only "missile requires VTOL" is enforced.  Enforce the rest.

Excluding P_O when asking for P_N is now redundant.  Drop that from
msl_abm_intercept().

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>