Fix stride_stricks.as_strided function for object arrays

Currently, calling as_strided for object array results in 'TypeError: Cannot change data-type for object array.'. Fix so that dtype of new array is only set for void dtype, as originally intended.
Merge pull request #4408 from charris/backport-1.8-gh-4377

Fix stride_stricks.as_strided function for object arrays
DOC: remove mention of quickselect in argpartition docs

the default algorithm is introselect
DOC: add object as_stride fix to release notes
Merge pull request #4410 from juliantaylor/doc-updates-1.8

Doc updates 1.8
DOC: Use tp_basicsize, not NPY_SIZEOF_PYARRAYOBJECT, for allocation

As mentioned in #2975, add agreed upon text from #2980 to the release notes.

Closes #2980.
Merge pull request #4413 from bfroehle/patch-1

DOC: Use tp_basicsize, not NPY_SIZEOF_PYARRAYOBJECT, for allocation
BUG: fix non-c99 fallback for np.inf input to log1p/expm1

closes gh-4225
Merge pull request #4416 from juliantaylor/log1p-expm1-no-c99-1.8

BUG: fix non-c99 fallback for np.inf input to log1p/expm1
BUG: Fix infinite recursion in str.format of flex arrays (Fixes #4359).

The implemention of __format__ on generic objects (PEP 3101) was changed to use string conversion when no better method is found.
DOC: Update 1.8.1 release note issues with gh-4359.
Merge pull request #4417 from charris/backport-1.8-gh-4401

Backport 1.8 gh 4401
BUG: Only convert 0d arrays to scalars in power

Operations such as `x**array([2])` would convert the
2 into an integer and loose the dimension information,
because the array (at this time, it is deprecated),
supports `__index__` even though it is not 0-d.

This fixes it, by not trying the index machinery
when it was an array, since it is unnecessary.

Closes gh-4145
DOC: add fixed issue 4145 to release notes
Merge pull request #4419 from juliantaylor/scalar-0d

backport 0d array power fix to 1.8
REL: Release 1.8.1rc1
BUG: restore api for file npy_PyFile_Dup and npy_PyFile_DupClose

breaking the api breaks matplotlib build and pip installation.
Introduce npy_PyFile_Dup2 and npy_PyFile_DupClose2 as replacements
Merge pull request #4455 from juliantaylor/api-restore-1.8

restore npy_PyFile_Dup api for 1.8.x
BUG: Fix commutativity of {dot,multiply,inner}(scalar, matrix_of_objs)

Fixes #2469 and #4482. Relaxes fail condition to allow subtype as documented.
DOC: Add backport of gh-4483 to release notes.