Accept general <SECTS|SHIPS|PLANES|LANDS|NATS> argument instead of
just <SECT|SHIP|PLANE|LAND|NAT>.
edit with <KEY> <VALUE>... arguments applies the arguments to all
selected objects. Without such arguments, edit lets you edit the
selected objects interactively one after the other.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>