Show the location referenced by a given URL in the editor.
If the document pointed by this URL is different than the document currently
loaded in the editor page, this URL will be used to set the content to edit,
to solve relative references (eg: images) and to show the location pointed by the
URL reference part.
If the document pointed by this URL is currently loaded in the editor page,
only the reference part of the given URL will be used to show the corresponding location
in the editor.