New features

[fayeab]

closes #42

Hello,

I've added two features (filtering and deduplication criteria) for skope rules.

This work is an improvement of #42
We have 3 new parameters for SkopeRule class :

• "filtering_criteria" in place of recall_min et precision_min

filtering_criteria: dict, optional
                    default={'precision': 0.5, 'recall': 0.01}
    The criteria to be used for filtering the rules.
    In the form {criterion: min_value}.
    The keys can be among ('precision', 'recall', 'f1', 'mcc', 'custom_func').

• "deduplication_criterion" in place of the default F1 score deduplication criterion which was used in deduplicate function

deduplication_criterion: str, optional (default='f1')
    The criterion to be used for deduplicating the rules.
    Either 'f1', 'mcc' or 'custom_func'.

• "custom_func" parameter

custom_func: FunctionType, optional (default=None)
    A personalised function that can be used as either/both a filtering
    or/and deduplication criterion.
    Has to take 1 parameter (tuple of size 4) which is supposed to be the confusion matrix
    elements (tn, fp, fn, tp) (in that order).

[ngoix]

Thanks @fayeab for the good work
It is gonna be hard to get reviews on this as a whole though, I would split this PR into at least 3 new ones:

1. requirement updates and test updates / sample_weight renaming / data getters update
2. addition of filtering_criteria parameter
3. addition of deduplication_criterion and custom_func params

These PRs do not need to be independent and are probably to be based on each others 1. <- 2. <- 3.- shouldn't take much time to split the code and it will make the review process a lot smoother