drop out virt_lans than include virtual nodes, until I get Chad's
stuff integrated. Drop any pretense of supporting virtual nodes in a
LAN; just die. Add tunnels table DB upload; tunnels are created
in place of a vlan when the link includes a virtual node. The tunnel
info is based on the virt_lans info of course, so that the user gets
virtual devices with the appropriate IP address. There is some goo for
determining who is the server and who is the client, and making sure
that we start just a single server (in case a node has multiple
tunnels). Also add post pass over virt_trafgens table to make sure
that port assignments are unique (using new DB table). Oop, need to
add something to make sure that IP addresses are unique too!

Oh, clear out some obsolete code.