Bert extractor class

[homomorfism]

Implementation of bert feature extractor, followed by our discussion idea.

Didn't tried train model, based on the proposed hypothesis, only implementation

[implausibleDeniability]

To clarify: further work on this feature may be performed by anybody, not necessarily by @homomorfism

[DanisAlukaev]

LGTM!

[homomorfism]

@implausibleDeniability please check my changes

[homomorfism]

Tests are failing, do not merge

[homomorfism]

Now tests are ok

Please, do not merge changes: today l am planning to train classifier, based on (untrained) bert features and handcrafted features. And then we will push changes to develop branch.

[implausibleDeniability]

Shamil, reviewing many unrelated changes is not that easy =(

Why do you add text features extractor to the branch with bert features extractor? That confuses the review greatly. If it's possible, I would suggest to split the changes to several branches:

1. Checkout new branch from dev, for instance "text-features-extractor"
2. Cherry-pick relevant commits, where you add class TextFeaturesExtractor, from the current branch to the branch "text-features-extractor"
3. Remove irrelevant to the current branch changes (just removing the files, or reverting commits, whatever easier)

You may do this several times if it seems you can decompose the current branch to many brances

[implausibleDeniability]

Good Spellchecking btw!

[homomorfism]

I have added Cross Validation, that generates file with results in each split and overall mean score

[DanisAlukaev]

Indeed, big commit. Everything seems fine to me!

[implausibleDeniability]

Заебись, Шамиль =)