Consider relaxing non_exhaustive use across the crate

[sanbox-irl]

There are a significant number of structs, especially utilities, which have non-exhaustive placed on them, such as Align. I understand that non_exhaustive can be used to make all fields of a struct public which making it a semver hazard, but the library is still pre-1.0, and has no such semver promises. (remembering Rect::from_pos_size vs. just writing it out keeps getting me).

Is there any interest in a PR that would relax many of these restrictions?