Fixes ovr in the binary classifier case, and adds support for lists of feature arrays in the multiclass case.
Added make_fit_parameter method
dded tests to test_boosting
Added _check_sample_weight
Shifted the _check_sample_weight into BaseWeightBoosting class
GradientBoostingClassifier docstring incorrectly specified default for max_features as "auto" when it is None.
Merge pull request #3715 from trevorstephens/correct-gbc-docstring

GradientBoostingClassifier docstring correction
Merge pull request #3713 from akshayah3/Boost

More explicit error message in Adaboost
DOC Add solido testimonial

Fixes #3668.
FIX ovr predict_proba in the binary case

Previous commit fixed the shape, but swapped the actual probabilities.
Merge branch 'pr/3710'