Include itempile and use fromArrayIfArray so plugins can add recipes without including itempile

Both lines are equivalent:

recipes.registerAmorphous(['wood.plank', 'wood.plank', 'wood.plank', 'wood.plank'], new ItemPile('workbench', 1))
recipes.registerAmorphous(['wood.plank', 'wood.plank', 'wood.plank', 'wood.plank'], ['workbench', 1])

except the latter avoids the need to add a new itempile dependency (to
get the ItemPile constructor for new).
0.2.0