BUG: _alpha_grid undefined symbol
FIX: Weight impurity decreases with weighted_n_samples
TEST: add non-regression test
ENH: add weighted_n_node_samples property
Cleanup
FIX: Recompile _gradient_boosting.c
DOC: fix rest syntax
TEST: check with scaled sample_weight
Merge pull request #2836 from glouppe/tree-importances

[MRG] Fix for #2835
DOC: Entry for #2835 + Put together entries wrt. trees and ensemble
BF: Correct degrees of freedom in f_regression + test.
BF in f_regression: variable naming + use assert_*array*_almost_equal.
f_regression and degress of freedom: update whats_new + minor.
FIX error message with sparse precomputed kernels

Reported at SO, http://stackoverflow.com/q/21639685/166749.
Revert "FIX error message with sparse precomputed kernels"

This reverts commit 71fa2683def41e7b39b1f60bada4a289b71b04fd.

The issue is more complicated than I thought.
FIX error message with sparse precomputed kernels (second try)

This time, all tests pass.
MAINT optimize Spotify logo (- a few hundred bytes)
FIX restore _pairwise on SVMs

Added a comment explaining what this property does.

This time, did a *full* test and only got an unrelated error.
Sorry for the noise.
Fixed incredibly minor spelling mistake
Merge pull request #2840 from earino/develop

DOC Fixed minor spelling mistake