Fix grammar

it's should be its
DOC: write cost function of logistic regression.

I feel it important to state clearly what is the cost function of the
model because:

    * Some might want to compare their implementation against this one,
    in which case it is important to know exactly what is the form of the
    cost function

    * Furthermore since the models are quite inconsistent in terms of
    notation for the regularization parameter: some models in this
    module penalize by 1/C, others by alpha and others by alpha/2
fixed typo: diriclet -> dirichlet
Fix labels of inliers vs outliers

At least based on what svm.OneClassSVM does in the example linked from this document, the description was wrong; labels actually assigned are 1/-1 for good/bad respectively, not 0/1.
DOC adding return type and improving module doc
DOC numpydoc convention for Bunch-returning functions

Also cap lines at 80 chars, remove trailing spaces.

As suggested by @jnothman at
https://github.com/scikit-learn/scikit-learn/pull/3316/files#r14269818
FIX MinMaxScaler behavior on 1D inputs.
Lift division out of loop in _isotonic_regression.

I'm surprised the C compiler doesn't do this, but it seems
to make a difference in the benchmarks.

Conflicts:
	sklearn/_isotonic.c
DOC: fix classes not referenced in docs