Bump to 3.1.0.

Bump to 3.0.0.

Bump version to 2.0.4.

Bump version to 2.0.3.

Changes

- Replaced twoway crate with memchr

Improvemnts

- Added "multipart" keyword, PR: #37

Bugfixes

- Fixed multipart stream is incomplete issue
- Some other minor bug fix

Improvements
- Some internal breaking code changes

Bugfixes

- Use std::u64::MAX instead of u64::MAX

Improvements

- Added support for utf8 encoded field name and file name

Improvements

- Used `u64` as content-length instead of `usize`