Fix ray 3D/sphere 3D collision

* Add unit test for ray 3D/sphere 3D collision
Move game object children to a new child component
Move world object to children physic component

* Protect children component internal list
* Add enumeration support to children component
* Move ray trace selection to cursor object
Reimplement saving
Implement entity component system

* Add basic nodes (base, graphic, physic)
* Add basic systems (input, graphic, physic)
* Fix wrong location of camera FOV clamping
* Remove game objects
* Remove custom save objects for now