Bugfix: add type text as prop for jQuery < 1.8 in external resources
Trigger checkbox-click on add existing data
Add support for multiple external resources
Remove inline hidden style for duplicated external resources > 3
Bugfix: find correct duplicate button on insert existing multiple external resource-data
Improve user input validation. Donts submit form if date is not correct
Add asterix to required input fields
Change literal-help behavior. Init add expanded jsonld data
Merge remote-tracking branch 'origin/master' into professorenkatalog

Conflicts:
	js/rdform.js