BUG: only symmetrize matrix when it is not already symmetric
Merge pull request #4021 from jakevdp/fix_check_symmetric

BUG: only symmetrize matrix when it is not already symmetric
MAINT more informative assertion failure in test_common
Documentation of max depth parameter

Changed the docstring

Few docstring changes
Merge pull request #4026 from akshayah3/master

Documentation of max depth parameter in the DecisionTreeClassifier
Added feature to fix #1523
ENH decision_function now returns #votes and scaled scores.
TST Added test to assertain correlation of decision function and prediction
FIX Implemented _check_is_fitted for OvO similar to the one for OvR
FIX Correct and separate the scaling logic for scores
TST Add decision_function tests to check for votes/scores

ovo_ties test will use decision function to calculate votes and score.
COSMIT Undo aggressive pep8
ENH use the decision_function to compute the prediction
DOC Add doc entry for OvO explaining the tie-breaking using scores

DOC Minor changes in docstring of OvO's decision_function
ENH is_fitted check will be commonly performed by predict