changes; add optinal jailflag argument to TBIsNodeVirtual, and add some
constants for assigning port ranges to jailed nodes.

newwanode: Allow reuse of existing node. So, if called with an IP that
already exists in the DB, reuse those records (nodes, interfaces,
reserved) rather than creating a new one. The web page makes sure that
the calling node has a valid IP (REMOTE_ADDR equals IP it gives us),
so it typically means an exiting node is being reinstalled (happening
with RON nodes right now!).