Add option to restrict LassoCV to positive-only coefficients
Add option to restrict ElasticNet to positive-only coefficients; add test for this case, and the same for LassoCV
TST : speed up tests + cosmit
FIX : n_jobs was missing from LassoCV
update what's new
Changed assert_array_equal() in Line 45 and 46 to assert_array_almost_equal(,,decimal=5). This has fixed the AssertionError, which occurs during the installation test.
Merge pull request #2742 from ai8rahim/issue-2741

Changed assert_array_equal() in Line 45 and 46 to assert_array_almost_equal...
DOC clarify order of output in NB predict_proba
Small documentation fix: from CMS to VCS
Merge pull request #2743 from eltermann/doc_fix

Small documentation fix: from CMS to VCS
FIX don't put data in source dir in bench_covtype

When running under a tool such as @fabianp's profiler yep,
dirname(__file__) is the location of the tool's __main__.py
instead of the benchmarks directory.

Also, we shipped a tarball containing a large dataset before.
COSMIT tree: unused variable warnings and use for/range

Not recompiled with Cython, as line numbers still match up.
BUG fix unchecked mallocs in trees

All mallocs are checked now. Some notes for the next person to touch this
code:

* with gil: raise MemoryError() didn't work as expected, as a surrounding
  nogil block catches and logs the exception, then proceeds as if nothing
  happened.
* There were several opportunities for double free in the code. This is
  handled by letting the destructor handle the freeing.
* Similarly, constructors failed to set pointers to NULL so __dealloc__
  would try to free unitialized pointers.
* Out of memory might leave trees in an inconsistent state, but will not
  cause a double free. A subsequent successful fit should produce a
  consistent state, although I didn't test this.
* Replaced a free/calloc with a realloc; realloc(NULL, n) = malloc(n).
* free(NULL) is a harmless no-op per ISO C89.

Also performed an optimization: the pre-sort splitter was using size_t for
an array of booleans. unsigned char is faster and smaller.

Finally, fixed some cosmetic issues (long lines).
faster heapsort
working quicksort
insertionsort (might not work)