Show hyperlink affordances or actions

[csarven]

On link hover, user should have affordances/actions available for the target resource.

For example:

• show a preview including information about the document, e.g., title, summary, dates, authors, audience
• offer option to graph view
• indicate the type of relationship between the subject and the target link

Some of this can additionally be incorporated in CSS, e.g., cyan border(s) or background colour for citations.