Visibility modifiers

[iluuu1994]

Should we allow private cases? How would that work with pattern matching?

[iluuu1994]

Comment from @bwoebi:

Is there any case or reason why an enum should ever contain protected or private contents? I consider an enum to be a fully transparent object without hidden state - immutable and fully open. Enums are data, not state.

As such I would also drop the visibility modifier from associated values argument lists.

[iluuu1994]

We'll deal with this later on.