Add a metadata flag that's set when an empty rubber tree is placed in

the world (keeps it from regrowing into a full one)

node_defs.lua

@@ -451,6 +451,8 @@ minetest.register_node("moretrees:rubber_tree_trunk_empty", {
 		if not moretrees:node_is_owned(pos, placer) then
 			minetest.rotate_and_place(itemstack, placer, pointed_thing,
 				moretrees.expect_infinite_stacks, { invert_wall = keys.sneak })
+			local meta = minetest.get_meta(pos)
+			meta:set_int("placed", 1)
 		end
 		return itemstack
 	end