Additions

• Change license to MIT (#560).
• Lwt_fmt, an Lwt-aware version of Format (#548, Gabriel Radanne).
• Lwt_io.establish_server_with_client_socket (#586).

Bugs fixed

• Lwt_stream.iter_n: rename ?max_threads argument to ?max_concurrency (#581, Hezekiah Carty).
• PPX: reject match expressions that have only exception cases (#597, Raphaël Proust).

Miscellaneous

• Improvements to Lwt_pool docs (#575, Bobby Priambodo).
• Restore all PPX tests (#590, Jess Smith).