Deprecation warning when predict uses predict_storage fallback

Author: markotoplak

Orange/base.py

@@ -229,6 +229,9 @@ def predict(self, X):
         if type(self).predict_storage is Model.predict_storage:
             raise TypeError("Descendants of Model must overload method predict")
         else:
+            warnings.warn("Automatic fallback to predict_storage is deprecated. "
+                          "Models will need to implement predict.",
+                          OrangeDeprecationWarning)
             Y = np.zeros((len(X), len(self.domain.class_vars)))
             Y[:] = np.nan
             table = Table(self.domain, X, Y)