BUG: set needs-init flag for unicode dtype

Python >= 3.3 does not like printing garbage unicode so printing
np.empty(x, 'U') can throw UnicodeDecode errors.
It is probably easier to just require initializing the dtype as a whole
instead of trying to catching the decode error on all places where it
might occur. Hopefully 0 is a valid code in all codecs.
Closes gh-4994.
ENH: Implement sys.getsizeof(x) for arrays and scalars.

Fixes #2279. Stubs/declares __sizeof__ method to use nbytes attribute.
ENH: add dimensions and strides to _sizeof__ and handle not owning data
ENH: remove unnecessary copy of convolve inputs
Merge pull request #5001 from juliantaylor/sizeof

support __sizeof__()
Merge pull request #4997 from juliantaylor/unicode-init

BUG: set needs-init flag for unicode dtype
BUG: avoid NamedTemporaryFile for large file test

NamedTemporaryFile files can't be reopened on Windows.
TST: skip large file test on windows

nobody knows if it supports sparse filesystems, so just skip it.
Merge pull request #5005 from juliantaylor/use-tempdir-for-large-file

Use tempdir for large file
Merge pull request #5002 from juliantaylor/convolve-nocopy

ENH: remove unnecessary copy of convolve inputs
BUG: fix genfromtxt check of converters when using usecols

fixes an issue reported by Adrian Altenhoff where user-supplied
converters in genfromtxt were not tested with the right first_values
when also specifying usecols.
Merge pull request #5006 from dhomeier/ioconv_usecols

BUG: fix genfromtxt check of converters when using usecols
ENH: Speed up `unique` with `return_inverse`

This replaces a sort with fancy indexing.