experimental ordering of searches within same rank

giving preference to those without operator and housenumber
apply rank restrictions already when scanning search_name table

fixes #176
fix coordinate order for route parameter

fixes #174
add functional tests

These are the tests that were formerly located at
https://github.com/lonvia/test-nominatim
update osm2pgsql (empty waterways)

fixes #153
add simplified geometry index for reverse queries
change default nominatim path for tests to obvious '..'
remove special casing of houses and postcodes in place import
fix running of DB tests via Makefile

Selecting tags for tests to run does not work when the tags are
on the features instead of the scenarios.
update osm2pgsql (nameless landuses) and add tests for it
lower significance of postcodes in Singapure

Postcodes with 6 digits designate delivery points, i.e. houses.
fix adding of spaces in GB postcode

Based on https://github.com/twain47/Nominatim/pull/180 by arunkmp.