Add an option to osm2pgsql to create indexes on the hstore columns 

With this option (--hstore-add-index) osm2pgsql simply calls a CREATE INDEX on all of the hstore
columns using a GIN index.



git-svn-id: http://svn.openstreetmap.org/applications/utils/export/osm2pgsql@29257 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4