Derive Eq trait for FromHexError

[jmacadie]

Without this we cannot derive Eq on enums & structs that contain a FromHexError. It is trivial to derive since all the elements of FromHexError implement Eq already. From reading the docs I think that this type should implement Eq;

Implement Eq in addition to PartialEq if it’s guaranteed that PartialEq::eq(a, a) always returns true (reflexivity), in addition to the symmetric and transitive properties already required by PartialEq

I'm not sure if you've already considered this and rejected it but if not, including this would save me some hassle.

[DaniPopes]

Thanks! Sorry I missed this

[jmacadie]

No probs & thanks!