0.31:
  special case buffer_get_token with token length 1 through memccpy (almost 4x speedup)
  test for pread and use it instead of lseek+read in cdb and io_mmapwritefile
  add mmap_readat (like mmap_read but open by fd, not by name)
  add fmt_iso8601 and scan_iso8601 (time_t -> "2014-05-27T19:22:16Z")
  add fmt_netstring and scan_netstring (http://cr.yp.to/proto/netstrings.txt)
  add (fmt|scan)_varint and (fmt|scan)_pb_* (binary marshaling ala protocol buffers)