Series

Looking at the Google Knowledge Graph display for Dune Messiah
<http://www.google.co.uk/#q=dune+messiah> reminds me that we need to address
the issue of series.

Do we follow the model of TVSeries and TVEpisode ­ at least we would not
have to worry about a TVSeason equivalent ;-)

Then of course there are serials, but I think we should hold off opening
that can of worms until we have agreed some of the simpler stuff!

~Richard.