Encapsulate cleaning function and restructure

geocoder/extension/sql/0.0.1/10_aux_functions.sql

@@ -0,0 +1,8 @@
+-- Cleaning function
+CREATE OR REPLACE FUNCTION geocode_clean_name(name text) RETURNS text
+    LANGUAGE plpgsql
+    AS $$
+  BEGIN
+    RETURN regexp_replace(name, '[^a-zA-Z\u00C0-\u00ff]+', '', 'g');
+  END
+$$;