Removes obsolete parameter

Fixes #1476
Small style optimization
Merge branch 'master' of github.com:WoltLab/WCF
Fixes some label (group) management issues
Removes obsolete import
Adds default implementation of IApplication::__run()
Adds missing page titles in ACP
Fixed error message if updating package lists failed
Properly remove package archives upon success
Merge branch 'master' of github.com:WoltLab/WCF