Link and File images #1498

Just like article images, should we have (optional) Link and File images in core?

Requirements:

• New image column in txp_link and txp_file tables.
• (perhaps) New column showing thumbnail in tables on Content > Links and Content > Files panels.
• Ability to search by image id from each panel.
• New input field for a single textbox that takes an (optional) image ID on the Content > Edit Link and Content > Edit File steps. Callback would allow com_article_image (ahem, perhaps renamed com_content_image in future) to hook into these steps too to provide drag/drop and select from DB images.
• New tags <txp:link_image /> and <txp:file_image />, perhaps with accompanying conditionals.
• Internally add the image IDs to 'image' entries in $thislink and $thisfile.

Thoughts on adding these optional features? Plugin territory or core worthy?

[tangentially related: Section image and Category image could follow the same blueprint. Possible outlier is an Author image]