hold separate values for each of the two pipes. This allows us to
treat the links asymmetrically with respect to the delay node
configuration. Changes to tmcd to return the expanded info, and rework
(completely) delay_config to allow user to change the duplex
characteristics (just like before), or just simplex characteristics by
specifying the pipe number. By convention (I invented) pipe 0 is
traffic coming in on iface0. Of course, none of the front end stuff
has been changed, so the changing a single pipe does not cause
anything in virt_lans to be changed, so those changes will be lost at
swapout. Also get rid of all the ssh'ed pipe config stuff in
delay_config. Instead, add a client side script called update_delays
to /etc/testbed on the experiment nodes. After updating the delays
table, just ssh over and run that script, which calls the existing
code. Less distribution of knowledge.