We only want to scope (i.e. prefix with hostID) those addresses that are
deemed loopback, to disambiguate them. Otherwise, we want to leave
addresses in unscoped form, so they can be matched, and links between
communicating nodes properly made.
So, we make the isLoopback check in MakeAddressID, and omit hostID if
the address isn't loopback. So far so good.
But this breaks topology rendering, as we were relying on extracting
hostID from adjacency node IDs, to populate origin hosts in the rendered
node output. So we need another way to get origin host from an arbitrary
node.
A survey revealed no reliable way to get that information from IDs in
their new form. However, we have access to node metadata, so this
changeset introduces the OriginHostTagger, which tags each node with its
origin host, via the foreign-key semantics we'll use going forward.
- Use constructors instead of ScopeDelim everywhere
- Use constructors instead of IDDelim everywhere
- IDDelim is renamed EdgeDelim, for clarity
- Partial import of the new test fixtures, to be completed later
