Added support for Angular validation, making it possible to require that a title, description and/or link is specified for each item (see 43a1442).
Rather than adding a single image at a time, it is now possible so select multiple images to be inserted (see 9d9e393).
Fixed an issue with the grid editor where the editor configuration was stripped and not restored again when the Angular validation failed due to missing properties (see 4bbd1e2).