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
escape the italics bold and monospace examples

since this is meant to be read in rendered form, and there are examples of these scattered through the text otherwise
MAINT: linalg: use sizeof instead of magic constant

Allows changing the error message at some point.
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.
Merge pull request #5012 from jaimefrio/faster_return_inverse

ENH: Speed up `unique` with `return_inverse`
BUG: potential memset on NULL in allocator cache
Merge pull request #5013 from larsmans/c-fixes

Small fixes, including a memset(NULL, c, n)
MAINT: use a structure as cache buckets
Merge pull request #5014 from juliantaylor/cache-struct

MAINT: use a structure as cache buckets