When roads cross boundaries, both administrative entities should
be added to the address list, so that both entities can be used
for searching. Also allows in a second step to better sort out
addresses of POIs on such roads.
Fixes#121.
The interpolaton computation needs information from the osm2pgsql
slim tables which may not be available when the data is inserted.
Insertion now only adds a line with basic address information to
location_property_osmline. The line is then split during the
indexing, leading to more lines (which are complete in that case)
being inserted.
Fixes#598.
