Small optimization
Merge branch 'master' of github.com:WoltLab/WCF
Small optimization
Language clean up
Fixed stacking of slashes if WCF is in document root
Merge branch 'master' of github.com:WoltLab/WCF
Added missing language variables
Merge branch 'master' of github.com:WoltLab/WCF
Small optimization
Disabling buttons during installation on click
Merge branch 'master' of github.com:WoltLab/WCF
Applying showOrder for ACP menu items

Fixes #1354
Added event for stylesheets in ACP header template

Fixes #1341
Fixed empty birthday in message sidebar
Merge branch 'master' of github.com:WoltLab/WCF
Added missing permission
Improved system requirements check
Fixed checkboxes not being recognized in search input
Using hidden input fields rather than mirroring checkboxes
Updating minified JavaScript files