Similar to assuming a selection box for the nodebox drawtype, minetest.register_item() now assumes a selection box for the fencelike drawtype.

Most modders would otherwise forget to explicitly define this, and generated nodes aliased from mods would wall-off caves

old_craft_grid, craft_inv) and
minetest.register_craft_predict(itemstack, player, old_craft_grid,
craft_inv)

This not only makes the vector functions faster, but also makes them more
consistent with other functions.