ENH: use lgamma function from John D. Cook

Conflicts:
	sklearn/metrics/cluster/expected_mutual_info_fast.c
	sklearn/utils/lgamma.cpp
	sklearn/utils/lgamma.pyx
	sklearn/utils/setup.py
Merge branch 'master' into lgamma_port

Conflicts:
	sklearn/metrics/cluster/expected_mutual_info_fast.pyx
Merge pull request #1529 from vene/lgamma_port

[MRG] Added lgamma Cython interface to utils for MSVC