* Implement `ConstantTimeEq` for `Group` and `Group::Scalar`
* Changed `expand_message_xmd` `dst` parameter to `GenericArray<u8, D>`
* Remove allocation for `dst_prime` in `expand_message_xmd`
* Remove allocation for `msg_prime` and `b` in `expand_message_xmd`
* Remove unnecessary references in `expand_message_xmd`
* Return `GenericArray` from `expand_message_xmd`
* Oxidize loop in `expand_message_xmd`
* Remove allocation for `b` in `expand_message_xmd`
* Remove allocation for `xor`
* De-duplicate code in `expand_message_xmd`
* Remove unnecessary features
* Make ristretto optional and export all backends
* Make `rand` optional
* Fix wrong documentation
* Document `rand` feature
* Remove empty line
* Fix rustfmt
* Fix testing with other backends
* Iterate by value in `expand_message_xmd`
* Fix typo
* Rename `ristretto_x` features to `ristretto255_x`
* Remove `rand` re-export
* Improve `expand_message_xmd` loop
* Remove unnecessary `#[doc(cfg())]`
* Remove unnecessary `pub(crate)` for `mod p256`
* Fix `p256` only build
* Rename `serialize` feature to `serde`
* Fix missing `Cargo.toml` update
