Replace `min_features` and `max_features` in ExhaustiveFeatureSelector` by `feature_range` and `recipe`

[rasbt]

For ease of use and versatility, the min_features and max_features parameters should be changed to

• feature_range: (min_val, max_val) or "all"
• recipe: "best" or "parsimonious"

Regarding feature_range, if "all" is selected, feature subsets of all sizes will be considered as candidates for the best feature subset selected based on what's specified under recipe.

Regarding recipe, if "best" is provided, the feature selector will return the
feature subset with the best cross-validation performance.
If "parsimonious" is provided as an argument, the smallest
feature subset that is within one standard error of the
cross-validation performance will be selected.

I.e., if feature_range=(3, 5) and recipe='best', the best feature subset with the best performance will be selected, and this feature subset can either have 3, 4, or 5 features.

Note that it would be best to deprecate min_features and max_features and default them to None. However if min_features and max_features are not None, they should have priority over the new parameters to avoid breaking existing code bases.