Runtime: work around 1s delay added when using twisted reactor's callLater.

Since wxPython4, using wxReactor from non-main thread was producing
exceptions in wxWidget's C++ code. Then reactor.run() was called from
main thread, and runtime's worker was delegating calls to reactor
with callLater(0, callable).

While this worked perfectly with wxReactor, it did introduce an unexplained
1 second delay to each worker call when using nomal linux reactors
(i.e. without wxPython). As a workaround reactor runs in a thread when using
twisted without wxPython

#!/bin/bash

# Run python example throug command line, and check usual output

coproc setsid $BEREMIZPYTHONPATH $BEREMIZPATH/Beremiz_cli.py -k --project-home ~/src/beremiz/exemples/python build transfer run;

while read -u ${COPROC[0]} line; do 
    echo "$line"
    if [[ "$line" == *Grumpf* ]]; then
        pkill -9 -s $COPROC_PID 
        exit 0
    fi
done

exit 42