BUG: np.unique with chararray + inverse_index

The call to `empty_like` was trying to use the `chararray` subclass,
which doesn't support the `np.intp` dtype.
Merge pull request #5099 from perimosocordiae/patch-1

BUG: np.unique with chararray + inverse_index
DOC: replacing old reference from EPD to Canopy
Merge pull request #5102 from dpinte/fix/epd_canopy

replacing old reference from EPD to Canopy
BUG: don't propagate subtypes from np.where

the C implementation cannot preserve subclass attributes, this needs a
python wrapper using indexing for subclasses.
closes gh-5095
BUG: check if object provides len() before trying to iterate it

some libraries want object arrays from objects that are iterable but
rely on not providing len() to get the right dtype from numpy.
closes gh-5100
BUG: check success of PyArray_DescrFromType in PyArray_InnerProduct

closes gh-5065
Merge pull request #5105 from juliantaylor/where-no-subtype

BUG: don't propagate subtypes from np.where
DOC: remove preservena reference from docstrings

preservena is not not implemented.
the putmask docstring is misleading, currently copyto is faster for
dense or sparse masks while putmask is faster for random masks.
[ci skip]
Merge pull request #5106 from juliantaylor/sequence-fix

BUG: check if object provides len() before trying to iterate it
Merge pull request #5107 from juliantaylor/na-doc

DOC: remove preservena reference from docstrings
Merge pull request #5104 from juliantaylor/inner-fix

BUG: check success of PyArray_DescrFromType in PyArray_InnerProduct
ENH: faster (branchless) logical_xor
ENH: logaddexp handling of same sign infs without warnings
TST: logaddexp and logaddexp2 with infs should issue no warnings
TST: extend truth table test to arrays with various dtypes
Merge pull request #5111 from larsmans/fast-bool

ENH: faster (branchless) logical_xor
DOC: Update PyArray_SearchSorted docs in c-api.array.rst
Merge pull request #5115 from jaimefrio/searchsorted-c-docs

DOC: Update PyArray_SearchSorted docs in c-api.array.rst
DOC: document NPY_BEGIN_THREADS_THRESHOLDED