Keep track of basic aliveness for peers regardless if direct or indirect connectivity and use this for multicast propagation. Also consolidate adding of active bridges via the same functor as regular multicast next hops.

node/Topology.cpp

@@ -89,7 +89,7 @@ SharedPtr<Peer> Topology::addPeer(const SharedPtr<Peer> &peer)
 	return p;
 }
 
-SharedPtr<Peer> Topology::getPeer(const Address &zta)
+SharedPtr<Peer> Topology::getPeer(const Address &zta) const
 {
 	if (zta == _r->identity.address()) {
 		TRACE("BUG: ignored attempt to getPeer() for self, returned NULL");