overhaul address computation

overhaul address computation

This is a complete rewrite of the selection of address parts to
be inserted into the place_addressline table.

The new algorithm selects for each rank:
* the boundary overlapping with the addressee and contained
  in the already selected boundaries of lower rank, or failing that
* the place node closest to the addressee that is contained in
  the already selected boundaries and in the influence radius
  of already selected place nodes of lower rank

Place nodes that are not contained in already selected boundaries
of lower rank are completely thrown away. All other candidates are
added as non-address parts.