Merge branch 'phpstan' into 'dev'

admin/ajax/project/create.php

admin/ajax/site/children/sort.php

lib/QUI/Groups/Group.php

lib/QUI/Mail.php

lib/QUI/Messages/Handler.php

lib/QUI/Package/Package.php

lib/QUI/Projects/Media/Utils.php

lib/QUI/Projects/Project.php

lib/QUI/Projects/Site.php

lib/QUI/Projects/Site/Utils.php

lib/QUI/Rewrite.php

lib/QUI/Security.php

lib/QUI/System/Console/Tools/CopyLanguageSites.php

lib/QUI/System/Console/Tools/GetSiteAttributes.php

lib/QUI/System/Console/Tools/Permissions.php

lib/QUI/System/Console/Tools/SetSiteAttributes.php

lib/QUI/Update.php

lib/QUI/Upload/bin/upload.php

lib/QUI/Users/Auth/QUIQQER.php

lib/QUI/Users/Manager.php