fixed #4062 - Several column don't sort at all (stable 3.1)

interface/web/mail/list/mail_user_stats.list.php

interface/web/mail/templates/mail_user_stats_list.htm

interface/web/sites/list/database_quota_stats.list.php

interface/web/sites/list/ftp_sites_stats.list.php

interface/web/sites/list/user_quota_stats.list.php

interface/web/sites/list/web_sites_stats.list.php

interface/web/sites/templates/database_quota_stats_list.htm

interface/web/sites/templates/ftp_sites_stats_list.htm

interface/web/sites/templates/user_quota_stats_list.htm

interface/web/sites/templates/web_sites_stats_list.htm