Add another untested fill algorithm and update LICENSE

fill_3d.lua

@@ -0,0 +1,53 @@
+-- Algorithm created by sofar and changed by others:
+-- https://github.com/minetest/minetest/commit/d7908ee49480caaab63d05c8a53d93103579d7a9
+
+local function search(go, p, apply_move, moves)
+	local num_moves = #moves
+
+	-- We make a stack, and manually maintain size for performance.
+	-- Stored in the stack, we will maintain tables with pos, and
+	-- last neighbor visited. This way, when we get back to each
+	-- node, we know which directions we have already walked, and
+	-- which direction is the next to walk.
+	local s = {}
+	local n = 0
+	-- The neighbor order we will visit from our table.
+	local v = 1
+
+	while true do
+		-- Push current pos onto the stack.
+		n = n + 1
+		s[n] = {p = p, v = v}
+		-- Select next node from neighbor list.
+		p = apply_move(p, moves[v])
+		-- Now we check out the node. If it is in need of an update,
+		-- it will let us know in the return value (true = updated).
+		if not go(p) then
+			-- If we don't need to "recurse" (walk) to it then pop
+			-- our previous pos off the stack and continue from there,
+			-- with the v value we were at when we last were at that
+			-- node
+			repeat
+				local pop = s[n]
+				p = pop.p
+				v = pop.v
+				s[n] = nil
+				n = n - 1
+				-- If there's nothing left on the stack, and no
+				-- more sides to walk to, we're done and can exit
+				if n == 0 and v == num_moves then
+					return
+				end
+			until v < num_moves
+			-- The next round walk the next neighbor in list.
+			v = v + 1
+		else
+			-- If we did need to walk the neighbor, then
+			-- start walking it from the walk order start (1),
+			-- and not the order we just pushed up the stack.
+			v = 1
+		end
+	end
+end
+
+return search