Merge branch...

Merge branch '1010-editor-the-prufungsziel-side-for-a-card-of-type-prufung-does-not-display-its-placeholder' into 'staging'

Resolve "Editor: The "Prüfungsziel" side for a card of type "Prüfung" does not display its placeholder"

Closes #1010

See merge request arsnova/flashcards!1154