change distance computation between place and address part

Instead of computing the distance to the centroid of the area
compute the distance of the area to the centroid of the feature.
This means we give preference to the area that covers the centroid.
It's still a heuristics but one that is a bit less random.

lib-sql/functions/postcode_triggers.sql

@@ -34,7 +34,7 @@ BEGIN
     NEW.parent_place_id = 0;
     FOR location IN
       SELECT place_id
-        FROM getNearFeatures(partition, NEW.geometry, NEW.rank_search)
+        FROM getNearFeatures(partition, NEW.geometry, NEW.geometry, NEW.rank_search)
         WHERE NOT isguess ORDER BY rank_address DESC, distance asc LIMIT 1
     LOOP
         NEW.parent_place_id = location.place_id;