Add set_world_* to SceneGraph
Add Matrix4x4::set_rotation()
Add Actor::update()
Update world poses in Actor's scene graph when the physics simulation is done
Pass scene graph and node index to actors
Update World
Remove debug code
Fix scene graph destruction
Add basic .physics compiler
Delete Shape
Add support to slope_limit, step_offset and contact_offset to PhysicsResource
Do not assert if allocate()/deallocate() not balanced
Add basic support to character controllers
Implement create/destroy/lookup_controller()
Add Actor::update_pose()
Remove unuseful helper functions
Add support to .physics to ResourcePackage
Add support for .physics to Unit
Better organize unit/sound creation
Delete unuseful stuff