Refactoring climpred to use classes under the hood

Many of the function signatures are the same; it might be good to use class inheritance to solve that.

Here’s an outline:

Comparisons():
    __init__:
        forecasts
        references

Alignment(Comparisons):
    __init__:
        alignment

Scoring(Alignment):
    __init__:
        metrics
        comparisons
        dimensions

HindcastScoring(Scoring):
    function
        self.forecasts
        self.references
        self.alignment
        self.metrics
        self.comparisons
        self.dimensions

PersistenceScoring(Scoring):
    function
        self.forecasts
        self.references
        self.alignment
        self.metrics
        self.comparisons
        self.dimensions

UninitializedScoring(Scoring):
    function
        self.forecasts
        self.references
        self.alignment
        self.metrics
        self.comparisons
        self.dimensions

Bootstrap(Scoring):
    __init__:
        resample_dimemsion
        significance_level

PerfectModelBootstrap(Bootstrap):
    function
        self.forecasts
        self.references
        self.alignment
        self.metrics
        self.comparisons
        self.dimensions
        self.resample_dimension
        self.significance_level

HindcastBootstrap(Bootstrap):
    function
        self.forecasts
        self.references
        self.alignment
        self.metrics
        self.comparisons
        self.dimensions
        self.resample_dimension
        self.significance_level

Items under __init__ are the necessary keyword arguments to inherit from that class, items under function are inherited arguments. Feel free to question/comment/suggest!

[aaronspring]

for discussion about API in with bootstrapping see #375

[bradyrx]

Still continuing on this front. We’ve prioritized getting the JOSS paper submitted with the current version. I’m also reviewing and patching ideas on xskillscore and climpred, which is pulling from my time on this problem. I’d say climpred_skeleton is about 2/3rds of the way there. Then the project of revamping this code is big. Will likely create a branch called e.g. classify_climpred and then do little edits to that as I build up the code base so it is easily reviewable.