ENH multinomial logistic regression using L-BFGS
ENH: Add support for class weights
FIX: Change alpha to 1./c
ENH: Merge MultinomialLR into LR with multi_class='multinomial'
ENH Added multinomial logreg to plot_classification_probability.py
ENH: Added multinomial option to LogisticRegressionCV
COSMIT: Minor doc fixes
TST: Tests for multinomial logistic regression
COSMIT: Made the following changes
1. Removed true from 'true multinomial loss'
2. Replaced OvA with OvR
3. Update whatsnew.rst
DOC: Improved documentation and error messages
DOC: Made the docs for LogisticRegression clearer
FIX: PEP8 Errors and unused imports
DOC: Changed docstring style for optional arguments
DOC document MultiLabelBinarizer.sparse_output param
DOC: Explicit instructions for Python3
Merge pull request #3586 from MechCoder/python3_installation

[MRG] DOC Explicit instructions for Python3
Added test for orthogonal LDA transform.
Fixed LDA transform.
Improved precision of the LDA orthogonality test.
forgot to remove an import