Remove too granular Copy implementation

[lvboudre]

Since an Address is a wrapper type around a Copy type ([u8;32]) it uselessly break older user-code during crates upgrade which didn't required copy in older version of the crate. Moreover the feature-flag copy is not documented in the documentation

[febo]

Since an Address is a wrapper type around a Copy type ([u8;32]) it uselessly break older user-code during crates upgrade which didn't required copy in older version of the crate.

The rationale is to avoid unintentional copies when writing programs, as discussed here. Versions v1.1 and v2.0 are compatible, which should help with upgrades.

Moreover the feature-flag copy is not documented in the documentation

This is a good point – not clear why the documentation does not show the copy feature requirement for the impl Copy. I will have a look at it.

[lvboudre]

I guess its subjective, since Pubkey is constant size implements Clone, PartialEq, Eq, Hash it makes sense to always implement Copy for such type. I never had issue with unintentional Copy seems a no-issue to me.