[Koha] Koha relevance ranking

[Elaine Bradtke]

When I first set up the catalogue we had truncated search switched on
and found the results were hopeless.
But even with it switched off, it picks up a lot of irrelevant records.
 One of the problems for us is that it searches the place of
publication.  Geography is a very important aspect of our collection,
and searches are often done on place names.  So someone looking for
material about London for instance will be presented a huge list of
items that were published in London.

If it were possible to specify which fields were searched in an
'unfielded' search, we could probably eliminate a lot of the false
positives.
While it is sometimes useful to search on a place of publication,
that's a very specific search, which should be done as an advanced
search.