(laun, launch_as, launch_missile, launch_sat): When an argument is

(laun, launch_as, launch_missile, launch_sat): When an argument is
bad, do not loop prompting, just fail.  That's what the vast majority
of commands do.

(launch_as, launch_missile, launch_sat): Don't zap the target
argument.  If the target is given as argument, launch all missiles at
that target.  Previously, missiles after the first prompted for
another target.