  o Minor features (control port):
    - Introduce new fields to the CIRC_BW event. There are two new fields in
      each of the read and written directions. The DELIVERED fields report the
      total valid data on the circuit, as measured by the payload sizes of
      verified and error-checked relay command cells. The OVERHEAD fields
      report the total unused bytes in each of these cells. Closes ticket 25903.
