Merge pull request #2516 from xillibit/k30_bugs12

Migration from tables "prefix_fb" does not works with Kunena 3.0 #2211
K3.1: blue eagle : Cannot hide admins in userlist #793 (backport fix)
K3.0: Hard coded word for backend template (Joomla 2.5) #2441 backport
Merge pull request #2544 from xillibit/k30_bugs8

K3.0: Hard coded word for backend template (Joomla 2.5) #2441 backport
Merge pull request #2543 from xillibit/k30_bugs4

K3.1: blue eagle : Cannot hide admins in userlist #793 (backport fix)
K3.0 | Userlist contains an error #2548
Merge pull request #2549 from xillibit/k30_bugs4

K3.0 | Userlist contains an error #2548
Missing text type on inputs added for poll in javascript
Fix Notice: Undefined property: KunenaViewTopic::$replycount in topic history
Merge pull request #2553 from mahagr/master

Fix Notice: Undefined property: KunenaViewTopic::$replycount in topic history
Merge pull request #2551 from xillibit/k30_bugs4

Missing text type on inputs added for poll in javascript
Anouncements list : colums separator for actions aren't displayed
Merge pull request #2552 from xillibit/k30_bugs8

Anouncements list : colums separator for actions aren't displayed
Fix Notice: Undefined property: KunenaAdminModelX::$context
Merge pull request #2555 from mahagr/master

Fix Notice: Undefined property: KunenaAdminModelX::$context
Update readme and pre-requiements check
Merge pull request #2556 from xillibit/k30_bugs4

Update readme and pre-requiements check
Fix for K3.0 : Lightbox : Long file names are not trimmed #2547
K3.0 With attachments-limit you can uploading them without limit #2558
K3.0 | The declaration "Show Super User in user list" contradicts itself #2559

Fix desc language
Change setting to Extra-Userlist