Organize the character hierarchy

The main rule is: CharacterBody and CharacterActor should always be in the root object (the "character" object).

You can be creative with the rest of the components.

The demo characters use the following hierarchy:

Root	Contains CharacterBody and CharacterActor
Graphics	Contains the visual elements of the character, from sprites to animated 3D meshes.
States	Contains the CharacterStateController and every CharacterState related to the character
Actions	Contains the CharacterBrain and all the AIBehaviours (AI characters).
Environment	Contains the MaterialController (used by some of the states included in the Demo)