First-class support of primitive Enums

[danslapman]

.. instead of by-hand encoding using alt's. This should also include kind of morphling-enumeratum module

[danslapman]

After a short investigation I found, that there is no need to do anything specific to naturally support enumeratum, this only need to be documented.

[danslapman]

https://gist.github.com/danslapman/dd7a8742817159d818697738b136e646