Reorganize the Queueing Discipline configuration tab

The Queueing Discipline tab in the default state did only show a blank check box.
To let the user know what is configured expose the queueing discipline and
the queue setup script unconditionally. The ECN settings stay hidden under control
of the advanced configuration checkbox. The "Show Dangerous Configuration" check box
now allows to define one string for ingress and egress each that is appended
to each tcx command line setting up each qdisc (under AQM control).
This allows easier access to the more specalized options of each qdisc for testing and research.
Since there is no checking whatsoever perfomed on these two strings
ths option is truely for experts and hence dangerous.