* Changed all instances of np.array in docstring to np.ndarray
* np.array is NOT a proper class name it is just a function to
create np.ndarrays and therefore should not be parameter class
* Black formatting compliance
* Makes some methods private that are not intended to be user-facing.
* Adds experimental module with fasttext.py and coteaching.py
* Adds header descriptions to code files which will render in docs
* Many miscellaneous fixes
Ulyana