Replace deprecated methods: (#179)

- 'setting_get' with 'settings:get'
- 'setting_getbool' with 'settings:get_bool'

item_transport.lua

@@ -1,6 +1,6 @@
 local luaentity = pipeworks.luaentity
-local enable_max_limit = minetest.setting_get("pipeworks_enable_items_per_tube_limit")
-local max_tube_limit = tonumber(minetest.setting_get("pipeworks_max_items_per_tube")) or 30
+local enable_max_limit = minetest.settings:get("pipeworks_enable_items_per_tube_limit")
+local max_tube_limit = tonumber(minetest.settings:get("pipeworks_max_items_per_tube")) or 30
 if enable_max_limit == nil then enable_max_limit = true end
 
 function pipeworks.tube_item(pos, item)