Add queue objects to lan nodes. Also add a second hack class (LLink)

that allows the user to get a handle on that queue object so it
can be changed. Add a routine (lanlink) to the sim class that operates
much like link command (gets the hack class, which in turn is used to
get the queue object).

Note, there needs to be some work done in the event parser in sim.tcl
to deal with lan queues (assumed to be link queues). I'll take care of
that later.