Create event sequences to do the equiv. of start- and stop-experiment.
Rather than using those scripts, you now can use start-run and stop-run
which are just wrappers around tevc to trigger the sequences.

This checking is backward compatible in the sense that you can continue to
use start- and stop-experiment and should never notice a thing.

The new event model doesn't support a couple of things that the old script
based execution did, most notably, you cannot change command line arguments.
It does support real vs. fake runs.