Added a test on hashing vectorizer behavior with np.nan input.
PEP8 line length fix.
Changed solver from 'dense_cholesky' to 'cholesky' to eliminate deprecation warning.
MAINT ensure that examples figures are displayed in the correct order
MAINT: more explicit glob pattern in doc generation
Replaced assert_raises with assert_raise_message as the point is to make sure the exception message is clear.
Merge pull request #3378 from kastnerkyle/dense_cholesky_warnings

[MRG] Eliminate dense cholesky warning during tests
Additional skipping for omp_cv
Put check_travis in the correct place so that other tests are not skipped, and changed the CCA check to be more explicit.
Lift division out of loop in _isotonic_regression.

I'm surprised the C compiler doesn't do this, but it seems
to make a difference in the benchmarks.

Conflicts:
	sklearn/_isotonic.c
DOC: more readable whats_new
DOC: fix classes not referenced in docs
FIX: check with tolerance on lars_path

Hopefully this will fix issue #3370 but I haven't checked.
Cosmetic np.abs -> abs
DOC Refreshed the documentation to install scikit-learn
TEST: metrics sample_weight test: almost_equal

The test was too strict and failing on certain boxes
Added additional skip checking for train and pickle tests
MAINT: skip some unstable transformers test under Win 32
MAINT configure Windows CI with appveyor.com
DOC various typos and fixes for the installation doc