DOC fix opaque background glitch when hovering example icons
FIX better RandomizedPCA sparse deprecation
Merge pull request #3470 from ogrisel/fix-sparse-randomized-pca-deprecation

[MRG] better RandomizedPCA sparse deprecation
added quantile strategy to dummy classifier
replaced quantile by percentile, added docstrings
switched back to quantile
final commit
forgot to save the file
removed blank lines, added default alpha param
added backport for axis keyword in scipy.scoreatpercentile
added quantile strategy to dummy classifier
replaced quantile by percentile, added docstrings
switched back to quantile
final commit
forgot to save the file
added backport for axis keyword in scipy.scoreatpercentile
removed scoreatpercentile axis dependency in the dummy tests
typo
fixed import
fixed axis keyword mistake