Update nxupdate command. (#616)
Update nxupdate command. (#616)

This removes the issue of having to update both .90dns and .nxupdate whenever the 90DNS IPs change. Furthermore, the 90dns command has exact setup instructions rather than just vaguely telling the user to set them blindly.
ihaveamac/Kurisu,916253/Kurisu,thedax/Kurisu