The main additions consist in checking for (and exiting on) wrong RTM detection
line readout, which indicates either a missing RTM, or that the Schmitt trigger
is a dud.

Then, the script also exits when the response of the PTS user to the questions
about the connections is a "no".

These two changes are both done to not waste time and energy on performing tests
on fundamentally wrong test conditions.

Finally, the pulses are enabled when performing fail-safe tests (MUX sel lines
"11"), since otherwise the test would pass without giving any useful information
on this test, as the HDL behaves in the same way if the RS-485 xceivers are
disabled or if they are in fail-safe.