Upgrade StorageOwn media-type for edited volumes
Today you have to use the "book"-mediatype for edited volumes and then have to change the author-fields manually to the editor-fields. It would be more comfortable, if edited volumes have their own media-type with editor-fields instead of author-fields, so that you don't have to edit them manually every time. (And adding articles to this edited volume should only have the relevant fields for this article, e.g. article-author(s), article-title, page-numbers.)