0.32:
  remove OpenBSD #warning (obsd maintainer says no longer needed)
  move headers to <libowfat/> upon install
  fix fmt_ip6 (Erwin Hoffmann)
  add MSG_ZEROCOPY support (only used for buffers >8k)
  use writev in buffer_put for a slight perf improvement
  add experimental iom API for multithreaded I/O multiplexing (in io.h)