Add hover behaviour for grey points

[ritagonmar]

When you hover over the grey points (unlabeled) in the general view, the box with the title and journal does not appear. I would suggest to add it at least in the general embedding/first view, even though I don't see a downside to having it in the other views too.

[bmschmidt]

Let's see if it ends up looking weird to just leave it on everywhere--added in most recent commit.