LAN nodes are no longer treated specially. Instead, I've introduced
the idea of 'static' types (old-style types retroactively become
'dynamic' types). While a pnode can only satisfy one dynamic type at a
time, it can always satisfy its static types (assuming it has enough
capacity left.) Static types are flagged by prepending them with a '*'
in the ptop file. So, for example, you may give switches the
'*lan:10000' type so that they can satisfy virtual LAN nodes. Of
course, other pnodes can have this type too, so that we can get
'trivial LANs'.

Actually, removing special treatment for LANs cleans up a lot of code.
However, it may have some negative impacts on solutions, since we're
not as smart about where to place LAN nodes as we used to be (they get
annealed along with everything else, and not migrated.) I haven't seen
any evidence of this yet, however.

This leaves us with a single type of special pnode, a switch.

Also added a new bit of syntax in pto...