remove __non_exhaustive members, add non_exhaustive attribute instead

[FauconFan]

As stated in #1835, I deleted every non_exhaustive members and added the #[non_exhaustive] attribute.
There are two more structs that may benefit from this: the Chapter struct and the Theme struct. The remaining structs have either a private member either all public members and doesn't deserve the attribute (to my opinion).
I could have put this attribute to enums as well, but this and adding attribute to the two structs above would be a breaking change. The page reference for non_exhaustive attribute. So I let this up to review.

[Dylan-DPC]

Thanks

[ehuss]

Sorry, I'm maybe a bit confused. This is a breaking change, and #1835 explicitly says this should be done for the 0.5 release. Unless I'm misunderstanding what the intent was here, can you please revert this change?

[FauconFan]

Well, maybe i'm wrong, but adding the #[non_exhaustive] attribute is not a breaking change if there were already private members right ?
I was talking about breaking change for other structs / enums.

[ehuss]

It is unfortunately exposed to preprocessors. #1571 contains some more information.

[FauconFan]

Oh yes indeed, sorry for that, it makes sense, now !

[FauconFan]

Well maybe it makes sense to create a new branch for release 0.5.0, then ?

[Dylan-DPC]

Ah my bad.

Nah i wouldn't recommend having a another branch - having 2 active branches makes it annoying to maintain and keep up to date. I would prefer holding this or having an open pr till 0.5 lands