Further support Read/Write Tag Fragmented byte offsets; Version 2.8.3
o Add Tag...+<offset> support to cpppo.server.enip.client, to allow
  the specificiation of a byte offset in Read/Write Tag Fragmented
  requests.
o More clearly name the Logix.request_elements method, and only
  examine a supplied .offset in Read/Write Tag Fragmented requests
  and replies.