While previously the content of addr:* tags was only added
to the list of address search keywords, we now really look up
the matching place. This has the advantage that we pull in all
potential translations from the place, just like all the other
address terms that are looked up by neighbourhood search.
If no place can be found for a given name, the content of the
addr:* tag is still added to the search keywords as before.
place=postcode places are artificial places that collect addr:postcode
points for aggration. They should neither show up in the address nor
be searchable. That means that there is no need to index them at all.
Only let boundary=postal_code through which define correct areas for
postcodes.
With ranks being dynamically changed through linking of places,
it is important to reset the ranks on update, so that changes
of the rank due to changes in linking are correctly taken into
account.