Note:  "sfnodes" is descended from  "scifi_nodes" by D00Med,   but the
code has been significantly reworked except for the chests module.

License for chest code:
Copyright (C) 2011-2012 celeron55, Perttu Ahola <celeron55@gmail.com>
LGPL 2.1

License for other code:
(c) 2016 D00Med <heiselong@gmx.com> and OldCoder (Robert Kiraly)
LGPL 2.1

License for images:
CC-BY-SA 3.0 Unported with attribution to D00Med.