Manage focus with episode order controls

[lukavdplas]

Problem: If you use keyboard controls to move an episode up/down in the narrative order, it makes sense for the user that the focus is kept on the same episode. This also enables to user to hit Enter a few times to move an episode further. Right now, this works when you move the episode down, but when you move it up, you lose keyboard focus and have to find your way back to the same episode.

I recently worked essentially the same control in another application, see CentreForDigitalHumanities/I-analyzer#1747 , which implements a solution to this problem. The code can't be copied directly because the HTML update is triggered in a different way, but perhaps this can still be transferred with minimal effort.