from wires table.  This is the first step to supporting more general
topologies.  There a couple testbed specific settings that are at the top
of the file.  Things such as the speed of our switch interfaces (since
we have no data on those interfaces in the DB), what type of switches we
have, and the fact that we have APCs that are in the nodes table but can't
be used as nodes.

This does generate slightly larger ptop files than the old version.  All
of the extra is isolated nodes so it only adds negligable runtime to
assign.