Make rank assignments configurable

The initial search and address rank is saved in a table
that is set up from a json configuration file. Ranks may
be assigned on a country level according to class and
type of the object. Special handling that depends on the
geometry or OSM type is still hard-coded in placex insert.

The new default config file mimicks the current assignment
as close as possible. A couple of exceptions have been
removed, most notably the exception for Irish townlands.

settings/defaults.php

@@ -49,6 +49,7 @@ if (isset($_GET['debug']) && $_GET['debug']) @define('CONST_Debug', true);
 @define('CONST_Pyosmium_Binary', '@PYOSMIUM_PATH@');
 @define('CONST_Tiger_Data_Path', CONST_ExtraDataPath.'/tiger');
 @define('CONST_Wikipedia_Data_Path', CONST_ExtraDataPath);
+@define('CONST_Address_Level_Config', CONST_ExtraDataPath.'/address-levels.json');
 
 // osm2pgsql settings
 @define('CONST_Osm2pgsql_Flatnode_File', null);