Scenes/Layers system

TL;DR: Add system of new user-created entities, allow adding/removing objects and rooms, and then showing/hiding the group altogether, optionally rendering the lights and shadows.

Naming

The suggested entities may be called Groups or Layers or Views or Scenes, it's not important at this point. In this post I will refer to them as Scenes.

Premise

Almost any map I create in DA has multiple floors/levels, and I end up creating several .dam files for each level. This is not very convenient, especially having to re-create shadows of the upper floors and roofs as if they were still present while the lower floor is shown.

Suggested implementation

Add a new tab to the left toolbar for Scenes management. Obviously, allow to Create and Delete scenes.
The Scenes tab should be represented by a list, with several switches next to each item:

• Make current (all created rooms and objects go there)
• Add/remove selected (toggle selected object or room being included in this Scene)
• Show items toggle (toggle models display, if it's disabled the objects are hidden but their shadows and lights are still shown)
• Drop shadows (separately toggle whether the objects and room cast shadows, so that two new states become possible: objects are hidden, but the shadows still rendered, and vice versa objects are shown but don't cast shadows)
• Emit lights (same for lights, convenient to add daylight sources and disable them altogether, or switch between night/day variations).

Anything not included in user-created Scenes may go to the "Default" item, effectively allowing hiding everything except e.g. top floor of the building. It may appear on Parchment, but with time, I hope, we will be able to export pngs/webps with transparency instead of parchment texture.

Upon Scene deletion it's better to present user with a choice to remove the included objects, or to delete the Scene only and keep objects not attached to any scene (or attached to Default).

Prior suggestions

There are similar suggestions here, however I hadn't found any suggestion with preserving shadows and lights. I don't know whether that's technically possible at all, but it's rather important.