Merge remote-tracking branch 'upstream/OpenOLAT_15.3' into OpenOLAT_15.3.uibk

Conflicts:
	src/main/java/org/olat/core/servlets/HeadersFilter.java
	src/main/java/org/olat/course/nodes/livestream/paella/PaellaFactory.java
	src/main/java/org/olat/modules/bigbluebutton/BigBlueButtonModule.java
	src/main/java/org/olat/modules/bigbluebutton/ui/EditBigBlueButtonMeetingController.java
	src/main/java/org/olat/modules/bigbluebutton/ui/_content/guest_join.html
	src/main/java/org/olat/repository/ui/author/AuthorListController.java
	src/main/webapp/static/js/js.plugins.min.js
	src/main/webapp/static/js/tinymce4/tinymce/plugins/olatmovieviewer/plugin.js
	src/main/webapp/static/js/tinymce4/tinymce/plugins/olatmovieviewer/plugin.min.js
	src/main/webapp/static/themes/light/content.css
	src/main/webapp/static/themes/light/content.css.map
	src/main/webapp/static/themes/light/email.css.map
	src/main/webapp/static/themes/light/theme.css
	src/main/webapp/static/themes/light/theme.css.map
	src/main/webapp/static/themes/openolat/content.css
	src/main/webapp/static/themes/openolat/content.css.map
	src/main/webapp/static/themes/openolat/email.css.map
	src/main/webapp/static/themes/openolat/theme.css
	src/main/webapp/static/themes/openolat/theme.css.map

Interface change:
	src/main/java/at/ac/uibk/course/CreateCourseContentStepForm.java
	src/main/java/de/bps/course/nodewizard/controller/RepositoryEntrySelectionController.java