WIP: releasing the GIL in the inner loop of coordinate descent
Replaced numpy calls with blas in dual_gap
Made the following fixes
1. Replaced l1_norm with dasum calls
2. Changed strides to n_tasks in ddot
Replaced multiprocessing with threading
ENH: Release the GIL for sparse coordinate descent
COSMIT: Replaced xrange with range
ENH: Release GIL in the gram variant
Replaced C ordered contiguity and added typed memory views
Added typed memory-views for H and XtA
Release GIL in the multi-task variant
ENH: Replaced double indexing as it causes python overhead
Merge pull request #3102 from MechCoder/gil-enet

[MRG+1] Releasing the GIL in the inner loop of coordinate descent