pbkdf2 0.4.0

Generic implementation of PBKDF2
Documentation
# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## 0.4.0 (2020-06-10)
### Changed
- Code improvements ([#33])
- Bump `rand` dependency to v0.7 ([#31])
- Bump `hmac` to v0.8 ([#30])
- Bump `sha2` to v0.9 ([#30])
- Bump `subtle` to v2 ([#13])
- MSRV 1.41+ ([#30])
- Upgrade to Rust 2018 edition ([#24])

[#33]: https://github.com/RustCrypto/password-hashing/pull/33
[#31]: https://github.com/RustCrypto/password-hashing/pull/31
[#30]: https://github.com/RustCrypto/password-hashing/pull/30
[#24]: https://github.com/RustCrypto/password-hashing/pull/24
[#13]: https://github.com/RustCrypto/password-hashing/pull/13

## 0.3.0 (2018-10-08)

## 0.2.3 (2018-08-30)

## 0.2.2 (2018-08-15)

## 0.2.1 (2018-08-06)

## 0.2.0 (2018-03-30)

## 0.1.0 (2017-08-16)