Json ld finetune 1

[tomschr]

This PR contains the following changes:

• Correct metadata

  • Rename "abstract" -> "description" and refactor code
  • Introduce "sameAs" property
  • Disable json-ld-version and json-ld-keywords
  • Use "Corporation" instead of "Organization" for default author and publisher

• JSON-LD: Rewrite author + authorgroup code

  • Simplify code and create a two set approach
  • If no (author/editor/corpauthor/contributor)s or authorgroup is found, fallback to a default corporation author
  • Add new parameters:
  • json-ld-fallback-author-name: The author's name
  • json-ld-fallback-author-url: the author's URL
  • json-ld-fallback-author-type: "Corporation" by default (but can also be a "Person")
  • json-ld-fallback-author-logo: the URL pointing to the logo