Fix defect in greenery -> state machine regular expression conversion
o Detect non-terminal loopback "dead" states, and ensure any
  transition into that state is retained as a non-transition.  This
  allows us to reject sentences detected as not in the regex grammar.
o Specify a NUL terminated string for enip communication_service
All unit tests pass, w/ new ListServices communications_service disabled
o Add specific symbols as explicit non-transitions, iff there is a
  whildcard transition from the state.