• API CHANGE: Functions in Lwt_io that were previously using a
  ~buffer_size argument now takes a ~buffer argument.
• Accept ?buffer argument in Lwt_ssl.{in,out}_channel_of_descr.
• Use newer Ssl bigarray read/write functionality to avoid
  allocation in Lwt_ssl.
• Fix non-reentrant function calls (#136)
• IPv4 multicast support.
• Add support for if%lwt in ppx extension.
• Add Lwt.return_some.
• Disable log syntax extension by default in ppx.
  Give [-log] as ppx argument to enable it.
• Nanosecond precision for Lwt_unix.stat.
• Minor fixes + documentation improvements.