fix_gnb_proba
DOC multi_output parameter on validation function
DOC: more explicit title

"Scaling strategies" was ambiguous: it could sound like how to rescale
data.
BUG: n_samples instead of n_features in cd_fast

Was causing a segfault under numpy master, that is more sensitive to
array index overflow. Our code was wrong, numpy is not to be blamed.
ENH: minor speed-up in k-means
ENH: Remove unused copy

One copy was done above the copy removed.

Validated IRL by @ogrisel
COSMIT: explicit comment
Changed f=open() to with open() as f to eliminate ResourceWarnings. Fixes #3410.
Merge pull request #3608 from agramfort/fix_gnb_proba

[MRG+2] fix_gnb_proba
Moved code out of context block where not required for #3612
Merge pull request #3612 from calvingiles/fix-resource-warnings

[MRG+1] Fixed ResourceWarnings from inside scikit-learn. Fixes #3410.
ENH cosmetic reorg of the confusion matrix example