Just to let everyone know that Withers are now back on Noobstown, you no longer need to use the villager to trade in your Wither Skeleton heads for a Nether star; you can now fight the Wither boss once again. As always this is only in the Nether and the End to protect the worlds though.
Enjoy this; I'm working through a big list of fixes and other features so more things will hopefully be coming soon too!