Alternate version of CompareVlansWithSwitches() to be used with the new -X option (synchronize tables) to snmpit. In this new version, a vlan is not considered changed (and thus needs to be deleted) if the port set has changed; snmpit -X can deal with that.
Alternate version of CompareVlansWithSwitches() to be used with the
new -X option (synchronize tables) to snmpit. In this new version,
a vlan is not considered changed (and thus needs to be deleted) if the
port set has changed; snmpit -X can deal with that.

Add new function RecordVLanModification() for snmpit to use when it
adds and subtracts ports from a vlan.

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