Previously, any error in assign wrapper would cause the experiment to
swap out because the "DB had been modified" ... well I have isolated
all of the changes that are made, and errors in assign_wrapper proper
no longer do that. tbswap now restores the experiment back the way it
was. Not that errors after assign_wrapper (like in os_setup) are still
a problem.

In addition, rather then kill off all of the vlans, leave them in
place and then do a comparison after assign wrapper, removing obsolete
and modified vlans only. I have made use of the obsolete vlans table
for this by having snmpit track its changes in that table. There is a
bunch of new code in Lan.pm for doing the comparisons.

revision ...

table.

not really able to test this stuff until it was running in the main tree.

lan_member_attributes, and ifaces. Making the world safe for protogenis.