add missing RealisticMaterial.clone()
add ISceneNode.hasController() to know wheter a scene node has a specific controller
fix RenderingController to have mesh/scene bindings counters in order to listen to each binding parameter only once and remove the callback when the corresponding binding is not used anymore
ScriptController will now lock its targets list before update in order to avoid race conditions during the traversal of the targets list
add missing use namespace minko_scene to allow the override of AbstractController.minko_scene::addTarget() and AbstractController.minko_scene::removeTarget()
fix DrawCall.setBindings() to avoid listening to the same scene binding twice