take more than one. This can increase efficiency, since, for example,
we now only have to lock the VLAN edit buffer once when tearing down
an experiment, instead of once per VLAN. There are still other
functions (setVlanOnTrunks comes to mind) that could benefit from this
treatment.

These optimization have been made only for Ciscos - minimal changes
necessary to keep Intel support working were made, but they will still
have the same old slow behavior.