Added 'relative' port counting. We store counters in the databse, and subtract that out form the numbers obtained from the switch.  So, we have a new option to 'zero' (store current values) of counters.  This is intended to be used at experiment swapin, but can also be used by experimenters whenever they want.
Added 'relative' port counting. We store counters in the databse, and
subtract that out form the numbers obtained from the switch.  So, we
have a new option to 'zero' (store current values) of counters.  This
is intended to be used at experiment swapin, but can also be used by
experimenters whenever they want.

Along with this, the following new options:
-z    Zero out counts for selected counters, after printing
-q    Quiet: don't actually print counts - useful with -z
-c    Print absolute, rather than relative, counts

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome