xF2 Add-on [XenDACH] LimitLanguageUsage 2.0.40

Fixed server error (https://xenforo.com/community/threads/xendach-limitlanguageusage.142506/post-1407619).

[Fix] Issue with language caching (https://xenforo.com/community/threads/xendach-limitlanguageusage.142506/post-1306265)

Thanks to @nocte

[Add] Prevent for enabling/disabling default language during editing language
[Add] Prevent for disabling default language in ACP language list

Thanks for your help @nocte, again..

[Add] Prevent storing an invalid language via account / preferences
[Add] Prevent storing an invalid language via frontend language choose or id

[Fix] Style issue in acp language table