auth.cas type mismatch for server port parameter

If auth.cas is configured using new configuration interface which replaces modifying configuration files, it will fail because phpCAS library expects server port to be an integer but it receives a string:

phpCAS error: phpCAS::client(): type mismatched for parameter $server_port (should be `integer') in /var/www/localhost/htdocs/ajaxplorer/core/src/plugins/auth.cas/class.casAuthDriver.php on line 42