Proposal: `Enum` class overhaul

[M Farkas-Dyck]

On 2017-12-13 08:22 PM, David Feuer wrote:
> I'm moderately opposed, on the basis that the Enum class is too fundamentally broken/meaningless to be worth fiddling with. It attempts to serve multiple barely-related purposes at once, and serves none of them terribly well.
I agree it's bad, but `..` syntax is defined in terms of it, and trying to introduce breaking modifications into base is like trying to introduce my head into a brick wall.