MAINT warn of future behaviour change proposed in #2610
Remove redundant yet unstable test_spectral_lobpcg_mode

The lobpcg mode is already tested in the test_spectral_clustering test.

LinAlgError was raised when executing test_spectral_lobpcg_mode on some
systems depending on the version of the scipy and LAPACK libraries.
TST: more robust test of dropping in Lars
TST: relax warning class checked in lars
TST: lars tests: more brutal ill-conditionning
ENH: make CD Lasso raise ConvergenceWarning
DOC: clear up the big elastic net confusion (I hope)

Several users have asked for LogReg w/ E-net (e.g. #3023). Did some
additional copyediting.
ENH: stable test + catch warning + pep8
ENH: more robust test_toy_bayesian_ridge_object
ENH: configure travis to also test old numpy & scipy
DOC: add some header doc to the travis scripts
More informative numerical error message in SGD

Also add a test.
cosmit
DOC: Fixed roc_curve docstring

It does not make sense for y_score of roc_curve to be binary.
MAINT remove _label attribute from SVC.

Fixes #1573.
FIX numerical stability issues on 32 bit platform

The gini index and the mean square error (variance) might differ due
to numerical instability. Since those instabilities mainly occurs at
high tree depth, we restrict the maximal depth.
MAINT lazily import scipy.cluster

Prevents PIL from being dragged along. Fixes #2961.
ENH micro-optimize a few tests
ENH micro-optimize fast MCD

Tests run 10-20% faster, which is what I was aiming for (it takes
almost 5s on my box).
FIX random_state validation on c_step

Got lost in e6003bc89. Also input validation on X.