Implement signal proxy messages

...ustjanne/libquassel/protocol/models/DccIpDetectionMode.kt

...tjanne/libquassel/protocol/models/DccPortSelectionMode.kt

...tjanne/libquassel/protocol/models/NetworkLayerProtocol.kt

...ustjanne/libquassel/protocol/models/SignalProxyMessage.kt

...otlin/de/justjanne/libquassel/protocol/models/TimeSpec.kt

...tjanne/libquassel/protocol/models/flags/BufferActivity.kt

.../justjanne/libquassel/protocol/models/flags/BufferType.kt

...justjanne/libquassel/protocol/models/flags/MessageFlag.kt

...justjanne/libquassel/protocol/models/flags/MessageType.kt

...n/de/justjanne/libquassel/protocol/models/types/QtType.kt

...justjanne/libquassel/protocol/models/types/QuasselType.kt

...ne/libquassel/protocol/serializers/HandshakeSerializer.kt

...ssel/protocol/serializers/NoSerializerForTypeException.kt

...ssel/protocol/serializers/SignalProxyMessageSerializer.kt

.../libquassel/protocol/serializers/SignalProxySerializer.kt

...ne/libquassel/protocol/serializers/qt/StringSerializer.kt

...tocol/serializers/signalproxy/HeartBeatReplySerializer.kt

...l/protocol/serializers/signalproxy/HeartBeatSerializer.kt

...el/protocol/serializers/signalproxy/InitDataSerializer.kt

...protocol/serializers/signalproxy/InitRequestSerializer.kt