Remove `use Enum` in favor of exposing variants automatically

[WilsonGramer]

For beginners, use Enum is arbitrary and confusing, and most programs define uniquely-named variants anyway. So, remove use Enum so that use is only used for importing files. If there's a conflict, you can still refer to variants on the type explicitly with Enum Variant (as it works currently).

[WilsonGramer]

Implemented in 82f7461!