* add filter field into OverlayOptions message
* chooseFiltered method, add excluded parameter in populate method
* change excluded type to []dht.NodeID in ChooseFiltered, change comment
* change name filter to excluded_nodes in proto
* implement helper function contains
* delete ChooseFiltered and add its functionality into Choose method to keep original author's history, add excluded argument into Choose calls
* regenerate mock_client.go
* regenerate protobuf
* update test case to use new IDFromString function
* remove old kademlia test code
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