109.13.00

- Added `Writer.write_line`, which is `Writer.write` plus a newline at
  the end.
- Added `?close_on_exec:bool` argument to `{Reader,Writer}.open_file`
  and `Async.Unix.open_file`.

  Made the default `close_on_exec:true` for `Reader` and `Writer`.
- Added a `compare` function to `Socket.Address.Inet`.