Add new preset estimators, metrics, and cv iterators

[reiinakano]

Sklearn has a TON of estimators, metrics, and cv iterators that could trivially be added to the xcessiv.presets package. I'm a bit focused on other issues to bother adding them all.

Anyone who can help add to the list can easily do so.

Adding preset estimators/metrics/cvs is very easy. There's literally no need to understand how the rest of Xcessiv works, just take a look and copy the patterns in the xcessiv.presets package. Also, add corresponding relevant tests for your addition.

Please keep PR's limited to one feature addition only for easy debugging and reformatting if needed. Of course, you can submit as many PR's as you like :)

[techscientist]

@reiinakano Hey, I just wanted to say that this is an AWESOME library! I'm currently a Kaggle novice, so this library is great! Also, I might be able to work on this later, so I'll send you a pull request once I've made some updates. Thanks!

[reiinakano]

@techscientist thank you for your kind feedback!

I would love PRs. Thank you!

[enisnazif]

Am also interested on working on this, I'll start soon :)

[robertmartin8]

At some stage I would like to contribute with this, but as I am new, I would like to clarify what you mean by

add corresponding relevant tests for your addition

What would be the scope of such tests?

[reiinakano]

You can just copy the style of existing tests for each one that you add :) it's probably simpler than adding the preset code itself