Entities + Component serialization

Etities and component are serialized
Bullet components are not serialized because bullet will be reimplemented soon.
Only serialization in XML and JSON are effective, their is still some problems with binary serialization.
WARNING : !!!!
Material have been changed so demos like SolarSystem + BulletImplementation do not render as expected. It'll be fixed in a new branch tomorrow and do not cause any problem to work on engine.