TLDR;

• need new major release bump
• saturating sub works only for self minus self outputs self and requires sub, which is not the case generally
• etc

LONG:

Covers what can work for current stable non zero.

What can be done?

1. detect Rust/MSRV lang version and gateNonZero<T> since it was introduced. Easy, dtolnay doing that.
2. detect this crate version major bump, and changebase traits relations. So we do not needAdd/Mul on non zeros. add VERSION_NUMBER_UNSTABLE feature like. So as for now just add new base traits.
3. One. Seems reasonable to add, but it tells some MATH props on interface, I can reproduce it without need toMul, with Checked only.
4. Port tests and some cast support fromImplement Bounded, ToPrimitive, NumCast, FromPrimitive for NonZero* #334 .Differs fromImplement Bounded, ToPrimitive, NumCast, FromPrimitive for NonZero* #334 by using generics.

I can do any version detection (Package/Rust) so can ensure it switched automatically.

Partially overlaps with next, but not same:

#85

#215