ENH: Call plot twice per class label rather than for every point.
ENH: remove offset calculations
ENH: use memset and memcpy when possible
ENH: make sort an inline nogil function
ENH: make node_reset/split/value gil-free
ENH: use npy_int32 type
ENH: Call plot twice per class label rather than for every point.
Merge branch 'plot_dbscan' of https://github.com/ericjster/scikit-learn into plot_dbscan

Fix formatting to be PEP8.
bug fixes in graph_lasso and moving non-custom log-likelihood definition to specific definition of cost
corrected sign error in _objective
pep8 compliance
Merge pull request #2502 from ericjster/plot_dbscan

ENH: Call plot twice per class label rather than for every point.
MAINT add authors to validation.py and pairwise.py
MAINT: use python setup.py clean in Makefile
FIX parallel FeatureUnion.fit and fit_transform

It didn't work previously because transformers were fit in another
process, and information they learned was not transferred back.
DOC docstring for extmath.norm
ENH refactor squared-norms computation to extmath

k-means can now use the memory-efficient dense implementation from
metrics.pairwise, while pairwise can use the fast sparse implementation
from k-means.
ENH use row_norms in KDE code

There may be other places where it is useful.
FIX fit followed by partial_fit in multiclass SGD

Fixes #2496 and includes a non-regression test. Since the introduction
of fast_dot (and NumPy 1.6), dot products between arrays of various
memory layouts have become fast enough to no longer require storing coef_
in Fortran order. The only noticeably slower operation is multiplying a
CSR matrix with a Fortran-ordered array, but then building the CSR matrix
in the first place is more likely to be the bottleneck.
FIX: clean-build target does no longer exist