Integrate AtmosObject with the tilemap

[henkhooft]

Summary

In the current situation every tile can contain an AtmosObject, however they are only created at runtime with a default air mixture. Integrate the AtmosObject with the tilemap so that we can set a gas mixture already in the editor.

Goal

• [ ] Make AtmosObject serializeable to allow setting it in a Tile. Set a default air mixture for tiles that do not have a preset atmosobject.

• [ ] Add the option to preset a gas mixture for an AtmosObject

• [ ] Add the option to preset the temperature

• [ ] Have a few popular presets in the editor. (air mixture, vacuum, pure oxy/co2/plasma)

[cosmiccoincidence]

Should be taken care of in #628 / #682

Edit: may actually be reserved to the atmos rework afterwards...