fix for BIESt 1283, closes #1283

app/controllers/admin/install.php

app/controllers/course/members.php

app/controllers/messages.php

app/controllers/oer/addfile.php

app/controllers/resources/booking.php

app/views/admin/install/layout.php

app/views/admin/install/prepare.php

app/views/admin/install/root.php

app/views/messages/overview.php

app/views/messages/write.php

lib/classes/AutoInsert.class.php

lib/classes/LinkButton.class.php

lib/classes/OAuth2/Exceptions/InvalidAuthTokenException.php

lib/classes/SystemChecker.php

lib/classes/restapi/RouteMap.php

lib/elearning/Ilias4ContentModule.class.php

lib/models/CourseDate.class.php

lib/models/Courseware/StructuralElement.php

lib/models/DatafieldEntryModel.class.php

lib/raumzeit/MetaDate.class.php