Citation: Inject current URL + date

[mokkalicious]

Most editions want to offer a citation reference / "How to cite" in some way.

Currently it is only possibly to provide a generic URL via the TextAPI, e.g.

To improve the citation, it would be better to inject the actual URL a user is currently on which includes the manifest, item and the opened panels (= bookmarking feature). However, this information is naturally not available in the back end.

A solution might be to offer some kind of placeholder on back end side in which TIDO then injects the URL of the current page.

Same holds for the date where we want the user's "today" to be displayed.