Serialization fixed + more (see comment)

- Save and load is fixed (binary, json, xml)
- Graphnode save and load
- Rigidbody, character controller save and load
- Dynamic create and load assets
- Assets load method modified
- Tags are serialized
- Move operator for entity data, bar code
- Skybox serialization
- Audio emitter and  listener save and load, playing audio play at where it end at serialization time

Close #91