* Reorganize perl modules by putting them under a perl5lib subdir. Improve
  installation so they are installed in the same place as before unless
  otherwise stated, but install under /usr/share/perl5 for Debian. Modify
  Makefile.in to properly deal with the above.
* Fix LinuxDocTools.pm permissions.
* Fix doc/Makedoc.sh to use the above location.
* No need to play with LinuxDocTools.pm in debian/rules. We already try Debian
  sgml-data site first when looking for sgml entities.