-track contact failures, last replied, and last requested. use this to provide a 'contact_is_good' property on Contact objects
-ensure no duplicate contact objects are created
-remove confusing conflation of node id strings with Contact objects, update docstrings
-move RPC failure tracking to a callback/errback pair in sendRPC (so the contact is only updated once)
-handle seed nodes during the join sequence by setting their node ids after they initially reply to our ping
-name all of the kademlia RPC keyword args, remove confusing **kwargs and dictionary parsing
-add host ip/port to DHT send/receive logging to make the results comprehensible when running many nodes at once
-adds reactor (clock) and reactor functions listenUDP, callLater, and resolve as arguments to Node.__init__
-set the reactor clock on LoopingCalls to make them easily testable
-convert callLater manage loops to LoopingCalls
The old code relied on the timing of DelayedCalls
to see what had been called or not, but unfortunately
we don't have a real-time OS so the timing on DelayedCalls
can only be approximate. Changed to explicitly keep
track of which calls had been made.
This simplifies the shutdown logic drastically, and I believe
we can take out the reactor.iterate() now
This reverts the change made in 693fef1964
Not sure why this is needed, but taking this out sometimes causes
`exceptions.AttributeError: 'Port' object has no attribute 'socket'`
to happen on shutdown.
