Missing Position Field Type in Matrix (Craft 3) Anyone know how to get the Position field type to show up in Craft 3 (RC)?

I have a Matrix field, and an Asset/Image field within that, and I'm trying to add a Position field to it.
The "Position" field type is retired in Craft 3. 

You can use this: http://plugins.supercooldesign.co.uk/plugin/button-box, or this https://github.com/Rias500/craft3-position-fieldtype instead, or just use plain old dropdowns.