Strassen::Lookup: add strassen_lookup_suitable directive after conversion
osm2bbd-postprocess: new target addr_sort

This replaces _addr with a sorted version of it, suitable for use with
Strassen::Lookup.
GeocoderAddr: refactored parse_search_string out of build_search_regexp
Strassen::Lookup improvements

* implemented delimited strings
* cease possible utf8 warnings
GeocodeAddr: prepare usage of Strassen::Lookup

A new geocode_fast_lookup() method exists now, but is not used,
because it is not capable of doing case-insensitive searches yet.