Add a changelog

# Change Log

## [Unreleased]

### Compatibility

* openssl 0.10 still uses openssl-sys 0.9, so openssl 0.9 and 0.10 can coexist without issue.

### Added

* The `ssl::select_next_proto` function can be used to easily implement the ALPN selection callback

    in a "standard" way.

* FIPS mode support is available in the `fips` module.

* Accessors for the Issuer and Issuer Alternative Name fields of X509 certificates have been added.

### Changed

* All constants have been moved to associated constants of their type. For example, `bn::MSB_ONE`

    is now `bn::MsbOption::ONE`.

* Asymmetric key types are now parameterized over what they contain. In OpenSSL, the same type is

    used for key parameters, public keys, and private keys. Unfortunately, some APIs simply assume

    that certain components are present and will segfault trying to use things that aren't there.

    The `pkey` module contains new tag types named `Params`, `Public`, and `Private`, and the

    `Dh`, `Dsa`, `EcKey`, `Rsa`, and `PKey` have a type parameter set to one of those values. This

    allows the `Signer` constructor to indicate that it requires a private key at compile time for

    example. Previously, `Signer` would simply segfault if provided a key without private

    components.

* ALPN support has been changed to more directly model OpenSSL's own APIs. Instead of a single

    method used for both the server and client sides which performed everything automatically, the

    `SslContextBuilder::set_alpn_protos` and `SslContextBuilder::set_alpn_select_callback` handle

    the client and server sides respectively.

* `SslConnector::danger_connect_without_providing_domain_for_certificate_verification_and_server_name_indication`

    has been removed in favor of new methods which provide more control. The

    `ConnectConfiguration::use_server_name_indication` method controls the use of Server Name

    Indication (SNI), and the `ConnectConfiguration::verify_hostname` method controls the use of

    hostname verification. These can be controlled independently, and if both are disabled, the

    domain argument to `ConnectConfiguration::connect` is ignored.

* Shared secret derivation is now handled by the new `derive::Deriver` type rather than

    `pkey::PKeyContext`, which has been removed.

* `ssl::Error` is now no longer an enum, and provides more direct access to the relevant state.

### Removed

* All deprecated APIs have been removed.

* NPN support has been removed. It has been supersceded by ALPN, and is hopefully no longer being

    used in practice. If you still depend on it, please file an issue!

* Some `ssl::SslOptions` flags have been removed as they no longer do anything.

## Older

Look at the [release tags] for information about older releases.

[Unreleased]: https://github.com/sfackler/rust-openssl/compare/v0.9.23...master

[release tags]: https://github.com/sfackler/rust-openssl/releases

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