Better separation of Foreground/Background scene in playback

[Bejoscha]

The "playback" section of the tool should indicated on the thumbnails both the playing foreground and the playing background scene (outlined in two different colours.) As both foreground and background scenes are stared "separately" when clicking on it, preserving the other (which is great), it would be good to have a way to stop them separately as well, i.e. have a separate "background stop" button.

It would also be helpful, if the background/foreground items on the Playback-section are visually separate (have the little icon and/or coloured border) and are spatially separated (left/right column)

[JakobKallin]

This is related to the scene model in general, which I will change for the next version of RPG Ambience.