Merge pull request #3261 from larsmans/test-interaction-features

TST test interaction features outside doctest
removed unused variables and imports, add used imports where missing.
COSMIT TYPO
Stop using some deprecated interfaces.
DOC typo in FastICA docs
Merge branch 'pr/3263': minor fixes from the 0.15.X branch
MAINT: restore -git version in the master branch after the last release merge
Incorporating @ogrisel's comments for simplification
More simplifications
Fixing simplification for clip
Adding test coverage for weight deprecation in IsotonicRegression and isotonic_regression
DOC: remove broken example link
MAINT removed shadowed broken test
DOC add Data Publica testimonial
Improving exception and warning coverage
Merge pull request #3250 from mjbommar/isotonic-refactor-2

[MRG+1] Refactor and clean IsotonicRegression
ignificant refactoring, will now automatically install Python, pip, and nose. Numpy and Scipy still require manual intervention
Fixed bug with append string getting double "_py_py"
WIP: releasing the GIL in the inner loop of coordinate descent
Replaced numpy calls with blas in dual_gap