CleverRaven/Cataclysm-DDA — pull request #6331 by Shoes01 (2014-02-27 02:12:47+00:00)
Title: Changed gas behavior to reflect entropy

Gases will only move to tiles that are less dense than itself. This means :

* Gases will not merge together to former stronger gases
* Gases will generally spread out as thin as they can get, rather than jiggle around randomly
* Gases, if in a closed room, will bump and flow and swirl around (super cool)