Derive Eq, Ord, PartialEq and PartialOrd on EnumMap<K,V> when K and V impl those traits

[klauria-factorial]

This would be broadly useful when using EnumMap<K,V> inside other structs where it's nice to be able to compare by value. If you think this would be good to add, I'm happy to take a shot, especially if you have some thoughts/opinions on how you think it should be done!

Thank you!

[sugar700]

EnumMap already implements Eq and PartialEq.

As for Ord, the issue is mostly it's not clear how it should be implemented and currently I didn't want to decide on any particular implementation.

[klauria-factorial]

If V implements Ord, I would naively think that a fixed-length array of V's can implement Ord by lexicographic comparison of elements. Would that have some downside I'm not thinking of?