QTI 2.1: better information in correction mode

in the assessment tool the tests can be corrected with the Correction. If you have a lot of tests, you save on the bottom. if you made an error e.g with the score, it does not save. the error message is only shown next to the corresponding item. if you have a long test you don't see it and close wizard --> no adaptations are saved

--> if error, red infobox appears with infotext

de: Die Änderungen können nicht gespeichert werden, da bei einer oder mehreren Fragen Fehler auftreten. Die detailliert Fehlerbeschreibung befindet sich bei der betroffenen Frage.
en: The changes cannot be saved, as there are errors in one or more question items. The detailed error description can be found by the corresponding question item.