Ensure we can properly reconstruct EtherNet/IP CIP CPF reply items
o Properly construct Get Attribute All reply.
o Correct technique for creation of empty (True) place-holder names
  in data artifact, for requests containing no data (eg. Get Attributes
  All, Write Tag [Fragmented] Reply.  Previous techniques sometimes
  put place-holder at wrong level, due to changing run-time context.
o Add handling for Logix Write Tag [Fragmented], and add Attribute
  __setitem__ to allow writing
o Complete the CPF, send_data, etc. produce methods.
o Add CPF and EtherNet/IP CIP request/reply reconstruction tests.
Working Register, Get Attribute All, Read/Write Fragmented
Merge branch 'feature-handle-replies'