The progressive mode is a Terraria-like crafting guide system that only
list the items in the crafting guide for which you already have the ingredients
in your inventory. The progressive mode is disabled by default and can be enabled with
`craftguide_progressive_mode = true` in `minetest.conf`.
Thanks to @kaeza and @Wuzzy2 for the idea.
See discussion on https://github.com/minetest/minetest_game/issues/1435
