A place needs all lower address rank object indexed to make up
the address. The search rank no longer ensures that as it can have
a different ordering than the address rank.
This switches indexing rank order to address ranks. Non-address
objects (with address rank 0) are indexed together with POIs.
When --drop is given, we can remove all node geometry information
already after the import with osm2pgsql. Also drop all unnecessary
tables before creating the final indices.
