r308: * dh_suidregister: Die with understandable error message if asked to

r308:    * dh_suidregister: Die with understandable error message if asked to
     act on files that don't exist.
   * dh_installchangelogs: to comply with policy, if it's told to act on a
     html changelog, it installs it as changelog.html.gz and dumps a plain
     text version to changelog.gz. The dumping is done with lynx.
     (Closes: #51099)
   * Dh_Getopt.pm: Modified it so any options specified after -- are added to
     U_PARAMS. This means that instead of passing '-u"something nasty"' to
     dh_gencontrol and the like, you can pass '-- something nasty' without
     fiddling to get the quoting right, etc.