Merge pull request #718 from karalabe/whisper-cleanup

ui/qt/qwhisper/whisper.go

whisper/envelope.go

whisper/filter.go

whisper/main.go

whisper/message.go

whisper/message_test.go

whisper/peer.go

whisper/peer_test.go

whisper/sort.go

whisper/sort_test.go

whisper/topic.go

whisper/topic_test.go

whisper/util.go

whisper/whisper.go

whisper/whisper_test.go

xeth/whisper.go