          Lobby
         /     \
      Library--Laboratory
       /
     books

There's no real way to generate a map of the books (at least not in any way
that would result in sensible output), so I decided not to. They're dynamically
loaded and thus may vary, and the only smart way of doing it, a keyword map in
the form "book <-- keyword --> other_book" wouldn't give a full picture.

Hence, they're just one node in the above map, although depending on play style
they might be many more.
