move word table and normalisation SQL into tokenizer

Creating and populating the word table is now the responsibility
of the tokenizer.

The get_maxwordfreq() function has been replaced with a
simple template parameter to the SQL during function installation.
The number is taken from the parameter list in the database to
ensure that it is not changed after installation.

nominatim/db/sql_preprocessor.py

@@ -89,8 +89,6 @@ class SQLPreprocessor:
         self.env.globals['db'] = db_info
         self.env.globals['sql'] = _setup_postgres_sql(conn)
         self.env.globals['postgres'] = _setup_postgresql_features(conn)
-        self.env.globals['modulepath'] = config.DATABASE_MODULE_PATH or \
-                                         str((config.project_dir / 'module').resolve())
 
 
     def run_sql_file(self, conn, name, **kwargs):