Add the 'dump' argument to the existing '--version' command-line
option to display the magic numbers used when validating save and
bones files for compatibility.
Nothing exciting, just a line of 5 hex values. I was going to also
list the values for however many save and bones files are specified
on the command line but it seems to need more effort than I care to
expend. And I hadn't made up my mind whether that should be done by
nethack, recover, or some new standalone program. [Single line of
relatively raw output is so that they could be compared more easily.]
nethack --version:bad-argument was writing a message to stdout and
then starting play--which immediately overwrites stdout. Have it
quit instead. Player wasn't trying to start a game and quitting is
what it does with --version:good-argument.