- disabled database logging of sql reconnect errors, fixed #3974

- remove certificate renew config on domain deleting

add translations to list-files



See merge request !357

First part of fix for issue #3896 - Unknown column 'default_mailserver' in 'field list' when saving client limits main template

Fix db stats - Please review

I think I found the fix... Please review if that's correct tough.
I just added  sys_group.groupid = web_database.sys_groupid AND

closes ispconfig/ispconfig3#3963
closes ispconfig/ispconfig3#3920

See merge request !355

fixed remove mail-backups (Bernd Kilmer)



See merge request !356

please review the change!

Fixed issue #3955 DNS module: Limit for maximum zones can be circumvented with "import zone file" function.
Removed TODO string in error template.