fix leaves growth error.

make growing leaves turn into alive leaves if they should do so.
previously, this didn't happen for leaves that exceeded their max
distance from supporting node.

mods/bg_tree/grow_leaves.lua

@@ -31,7 +31,10 @@ blockgame.register_increasing_abm({
 		-- this requires the API to add support for increasing ABM `action`:s to modify `data`.
 		local meta = minetest.get_meta(pos)
 		local distance = meta:get_int("leaf_distance") or 1
-		if distance >= max_grow_distance then return end
+		if distance >= max_grow_distance then
+			minetest.set_node(pos, {name = leaves_alive})
+			return
+		end
 
 		local sides = blockgame.vector.get_sides_of(pos)
 		for _, target in pairs(sides) do