Event specific banner/slides

One-sentence description

Event specific banner/slides.

Motivation

It is awesome and the standaard images get boring

Desired functionality

For an event it should be possible to add a slide, just as now possible for the front page. If the slide is added for an event, it might also be nice to automatically show it on the front page

Suggested implementation

Something like documents per event, but for slides I guess.

I honestly have no idea how much work it is but it seems nice