Add redirects for broken incoming links

[jhenstridge]

Looking at Google Search Console's 404 report, the following come up as broken links (with referers):

http://plug.org.au/events/seminar/
   - https://lists.plug.org.au/pipermail/plug/2006-August/071669.html
http://www.plug.org.au/archives/message/20060116.055959.f9633fab.html
   - https://debianforum.de/forum/viewtopic.php?p=374220
http://www.plug.org.au/archives/message/20060228.020931.240bcde2.en.html
   - https://www.csamuel.org/2006/02/28/leon-brooks-update
http://www.plug.org.au/contact.
    - https://lists.plug.org.au/pipermail/plug/2011-May/080649.html
http://www.plug.org.au/events/installfest.
    - https://lists.plug.org.au/pipermail/plug/2007-November/075909.html
http://www.plug.org.au/events/seminar/2004-07
    - http://www.groklaw.net/article.php?story=20040715111409931
http://www.plug.org.au/home
http://www.plug.org.au/index.php
http://www.plug.org.au/members
    - http://lists.plug.org.au/pipermail/plug/attachments/20170428/9b99d02e/attachment.html
    - http://lists.plug.org.au/pipermail/plug/attachments/20180808/a7ec6c55/attachment.html
http://www.plug.org.au/modules.php?op=modload&name=PostCalendar&file=index&type=view&eid=24
    - https://lists.plug.org.au/pipermail/plug/2002-June/031224.html
http://www.plug.org.au/modules.php?op=modload&name=Sections&file=index&re
    - https://lists.plug.org.au/pipermail/plug/2003-January/036908.html
http://www.plug.org.au/resources/newsletters
    - https://lists.plug.org.au/pipermail/plug/2012-April/081556.html
http://www.plug.org.au/user.php
https://www.plug.org.au/Constitution/Current
    - https://lists.plug.org.au/pipermail/plug/2018-February/083979.html

Most of these are internal links from our mailing list archives. Some seem to be truncated versions caused by line or word wrapping (e.g. http://www.plug.org.au/members seems to come from an HTML message with a word break: http://www.plug.org.au/members<wbr>hip).

If any have a reasonable target on the current website, we should add them to the redirect map.