Add support for allowed/denied IP/Mask

Login can be restricted to specific ranges of IP address or to a specific IP
address.

Please apply the appropriate SQL upgrade script to add the filter field to your
database.

The filter database field will allow to add other filters without requiring a
new database migration

sql/mysql/20191230.sql

@@ -0,0 +1,6 @@
+BEGIN;
+--
+-- Add field filters to user
+--
+ALTER TABLE `users` ADD COLUMN `filters` longtext NULL;
+COMMIT;