Update to 1.831
    
    - New upstream release 1.831
      - Separated documention of non-blocking I/O from error handling
      - Changed and documented behavior of readline to return the read data on
        EAGAIN/EWOULDBLOCK in case of non-blocking socket
        (see https://github.com/noxxi/p5-io-socket-ssl/issues/1)
    - Bumped release rather than version number to preserve likely upgrade path
      and avoid need for epoch or version number ugliness; may revisit this in
      light of upstream's future version numbering decisions