Random dungeon generator

[christiankolding]

@Jasoco: Yep, that's sort of what I am doing now - but I think I can implement it in a much more efficient way, if I store the positions of the existing items, instead of checking for neighbours.

@Lap: Thanks. I am sort of impressed by how good they actually look, since I don't really know how to program in Lua or have any game dev experience at all.