added BaseObjectWrapper as base class for: SpaceWrapper and ModelContainerWrapper
removed: ModelWrapperModel, now one Model doesn't need a wrapper
renamed: ModelWrapperSpace -> SpaceWrapper, now as a base class it has BaseObjectWrapper
renamed: Model::get_model_wrapper() -> Model::get_wrapper() - now it returns Wrapper object
removed logging from Model::get_model() and Model::get_wrapper()
field() methods don't take ModelWrapper** but Wrapper& now