eliminate reference loops created by use of %subs
* perl/Amanda/MainLoop.pod: document it
* installcheck/Amanda_Changer.pl installcheck/Amanda_Changer_compat.pl
  installcheck/Amanda_Changer_disk.pl
  installcheck/Amanda_Changer_multi.pl
  installcheck/Amanda_Changer_ndmp.pl
  installcheck/Amanda_Changer_rait.pl
  installcheck/Amanda_Changer_robot.pl
  installcheck/Amanda_ClientService.pl installcheck/Amanda_Device.pl
  installcheck/Amanda_MainLoop.pl installcheck/Amanda_Recovery_Clerk.pl
  installcheck/Amanda_Recovery_Scan.pl
  installcheck/Amanda_Taper_Scribe.pl installcheck/Amanda_Xfer.pl
  installcheck/amfetchdump.pl installcheck/amidxtaped.pl
  installcheck/amlabel.pl perl/Amanda/Changer.pm
  perl/Amanda/Changer/compat.pm perl/Amanda/Changer/multi.pm
  perl/Amanda/Changer/ndmp.pm perl/Amanda/Changer/robot.pm
  perl/Amanda/Interactive/stdin.pm perl/Amanda/Recovery/Clerk.pm
  perl/Amanda/Recovery/Scan.pm perl/Amanda/Taper/Scan/traditional.pm
  server-src/amcheck-device.pl server-src/amfetchdump.pl
  server-src/amidxtaped.pl server-src/amlabel.pl server-src/amrestore.pl
  server-src/amtape.pl server-src/amvault.pl server-src/taper.pl: use it

git-svn-id: https://amanda.svn.sourceforge.net/svnroot/amanda/amanda/branches/3_1@2857 a8d146d6-cc15-0410-8900-af154a0219e0