rename sql directory to lib-sql

Also introduces a separate constant for the sql directory, so that
it can be put separately from the rest of the data if required.

lib-sql/words.sql

@@ -0,0 +1,14 @@
+CREATE TABLE word_frequencies AS
+  (SELECT unnest(make_keywords(v)) as id, sum(count) as count
+     FROM (select svals(name) as v, count(*)from place group by v) cnt
+    WHERE v is not null
+ GROUP BY id);
+
+select count(getorcreate_postcode_id(v)) from (select distinct address->'postcode' as v from place where address ? 'postcode') as w where v is not null;
+select count(getorcreate_housenumber_id(make_standard_name(v))) from (select distinct address->'housenumber' as v from place where address ? 'housenumber') as w;
+
+-- copy the word frequencies
+update word set search_name_count = count from word_frequencies wf where wf.id = word.word_id;
+
+-- and drop the temporary frequency table again
+drop table word_frequencies;