integrates latest gossip package

packages/gossip/errors.go

packages/gossip/events.go

packages/gossip/manager.go

packages/gossip/manager_test.go

packages/gossip/proto/message.pb.go

packages/gossip/transport/handshake.go

packages/gossip/transport/proto/handshake.pb.go

packages/transactionspammer/transactionspammer.go

plugins/autopeering/plugin.go

plugins/metrics/plugin.go

plugins/statusscreen-tps/plugin.go

plugins/tangle/solidifier.go

plugins/tangle/solidifier_test.go

plugins/ui/ui.go