Merge pull request #2917 from ariddell/patch-1

DOC: Update dead link in cross_decomposition.rst
MAINT drop support for NumPy < 1.6.1
MAINT drop support for SciPy < 0.9

TODO: get rid of solve_triangular. Just replacing it by scipy.linalg's
breaks OMP and least-angle regression.
TST: test utils.extmath more robust
MAINT remove useless import
ENH more optimizations for RBM

Shaved off another ~12% on the digits example; the biggest part of the
savings is in _sample_visibles.
Fix a minor typo: 'They requires' should be 'They require'.
Merge pull request #2920 from yoni/master

Fix a minor typo: 'They requires' should be 'They require'.
[Cross Validation] Use itertools.izip consistently across Python 2/3
when computing folds in StratifiedKFold.

This isn't an especially hot code path, but it seemed to be preferable
for consistency.
Merge pull request #2925 from ajtulloch/izip-cross-validation

ENH Use izip consistently in StratifiedKFold
FIX #2924: make lobpcg test pass with reference and ATLAS impl of LAPACK
[tests] Use Python 3 zip/Python 2 zip consistently in tests
ENH/TST remove unnecessary sorts and complete testing for sparse median
MAINT: remove our solve_triangular

No longer needed, since we depend on scipy >= 0.9
MAINT: commit generated code
FIX + TST stability problems with scipy.special.expit

Fixes issue reported by @argriffing at #2882: expit is buggy in
SciPy < 0.14 (to be released). Switch implementation back to
old one based on stability test; toughened unit tests.
MAINT: scipy 0.10 and 0.11

linalg.solve_triangular does not have a check_finite keyword argument
Add test for _safe_split with pre-computed kernel.
Fix test failure on Python3.
More stable test problem for eigen_solver='lobpcg'