* Enable loading model from <1.0.0 trained with objective='binary:logitraw' * Add binary:logitraw in model compatibility testing suite * Feedback from @trivialfis: Override ProbToMargin() for LogisticRaw Co-authored-by: Jiaming Yuan <jm.yuan@outlook.com> Co-authored-by: Philip Hyunsu Cho <chohyu01@cs.washington.edu>