Merge pull request #2169 from mahagr/master

Fix #2168, #1676: Bad query in who is online uses too much memory
#2162 Long Filenames for Attachments
Optimize part to get subscriptions in backend
#2161 File Manager : All packed files are displayed with the same size
#2167 Vote Limiting In Polls Doesn't Work
Merge pull request #2172 from xillibit/k30_bugs8

#2167 Vote Limiting In Polls Doesn't Work
Merge pull request #2164 from xillibit/k30_bugs4

#2161 File Manager : All packed files are displayed with the same size
Merge pull request #2171 from xillibit/k30_bugs6

Optimize part to get subscriptions in backend
Merge pull request #2163 from xillibit/k30_bugs3

#2162 Long Filenames for Attachments
Fix regression #2173: Undefined property: stdClass::$time in getOnlineUsers()
Merge branch 'master' of github.com:Kunena/Kunena-Forum