work right when the administrator has modified their runtime environment
in a manner not anticipated by our script.
Requested by: Tom Maher <tardis@ece.cmu.edu>
Delete bogus localhost.rev.
Add prototype localhost.rev and a script to create it automatically.
(NB to installl people: you should ask ``do you have a full-time connection
o the Internet?'', run this script, and enable named if the answer is
yes.)