Make sure we can stop on waiting for ACK and G-Code msg dlg update.
* Added code to be able to exit Waiting fro ACK loop when user hits STOP
  button.
* Added NULL sw state and cmd ID, for ease of init vars.
* Upgraded G-Code msg to allow to continue with out having to close dlg
  and hit run again.
* Added re code for tinyG update machine status vars.