added ui skin
- added InputMapper for collection of keys
- added SettingsListener to change settings on key events
- added Collidable interface
- changed ModelInstance to CollidableModelInstance for easier collsion
detection
- changed GUIRenderer to HUDRenderer
- models -> model
- skybox rendered from mesh to instance
- hud renderer
- optimisation on octrees (colors on different sizes)
- changed structures
- interface for render and resize
- added sectors for spatial fragmentation