don't store hopcount in alt_route, it's not reliable
hop count would always point to the hop count of the trivial loop, e.g.

	A -> B -> C
	       <-

but that's ok, we just have to know that there *is* a different node with which we can reach e.g. B
don't remove expired route if there is still a valid alternative route
clean up fill_routing_table
put new routes in other_routes first
add skipped argument to simple_list_for_each_safe
fill routing table based on other_routes