Highlighting

This is a minor feature I've been missing for a while; the ability to highlight instances while comparing/discussing them.

I've kept your feature which allowed inspecting instances, but I chose to trigger it on double-click to enable highlighting on single-click.

I'm not sure about having the controller know about the DOM (which it has to do since it traverses the DOM to find the row that was clicked), so any other suggestions are gratefully accepted.

As a bonus feature, I also added the `table-hover` class to the table, to highlight rows on hover.