retreat lretreat: Be less loquacious when changing orders

retreat lretreat: Be less loquacious when changing orders

Instead of listing all the ships or land units ordered, just print how
many got ordered, and describe the order, like this:

    [0:640] Command : retr 2/3 bg itb
    2 ships ordered to retreat along path bg when injured, torpedoed, bombed
    [0:640] Command : retr 2 h
    1 ship ordered not to retreat

fleetadd doesn't list the ships it reassigns, either.  On the other
hand, stop lists the sectors it stops.  Perhaps it should be gagged,
too.

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