celeron55/minetest_game — pull request #66 by PilzAdam (2012-12-15 14:06:31+00:00)
Title: Add upside down slabs and stairs

If stairs or slabs are placed at the bottom of a node they turn into upside down versions of themselves.
Additionally an upside down slab can turn into a full block if a slab is placed at the bottom of it. Also upside down slabs are used when placing slabs at the side of upside down slabs.