user type unpacking implemented, unpack code reorganized

msgpack.h

@@ -7,6 +7,7 @@
 namespace MsgPack
 {
     QVariant unpack(const QByteArray &data);
+    bool registerUnpacker(qint8 msgpackType, unpack_user_f unpacker);
 
     QByteArray pack(const QVariant &variant);
     bool registerPacker(QMetaType::Type qType, qint8 msgpackType, pack_user_f packer);