File object support for imread and imsave
Changed parameter naming and added test for file objects
ENH: sparse: rewrite some lil methods in Cython for speedups
ENH: sparse: implement cythonized fancy setitem
ENH: sparse: use memoryview in _csparsetools
ENH: sparse: add scalar indexing fast paths to LIL
MAINT: sparse: document the _csparsetools.pyx file appropriately
MAINT: add _csparsetools to .gitignore
MAINT: drop Cython from .gitattributes (no longer in repo)
ENH: sparse/lil: minor improvements in LIL fancy indexing

As per review comments:

- explain and rename prepare_index_arrays
- indicate out-of-bounds column indices
- faster insertion in lil_fancy_get
- explain reason for preferring isinstance in scalar fast paths
Merge pull request #3356 from pv/lil-speed-cy

ENH: sparse: speed up LIL indexing + assignment via Cython
BLD: fix Bento build for addition of sparse._csparsetools extension.
TST: ndimage: close file obj in test
TST: remove usage of ``np.set_printoptions`` in sparse test.

Closes https://github.com/numpy/numpy/issues/644
TST: misc: add test for imsave
Merge pull request #3124 from pr-3124

ENH: misc: File object support for imread and imsave