Bug 13713: Follow-up removing biblioitem routines

Bug 13713: Follow-up removing biblioitem routines

There is no need to define biblioitem routines, if we can access them
via biblioitemnumber.
Note that we actually need a FK for biblio in the items table. Now we do
need the intermediate level via biblioitems in the Items.t code. Even better,
we should move biblioitem to biblio. Formally it is 1-n, but in reality it
is 1-1.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>