Faster version of ``np.isin`` and ``np.in1d`` for integer arrays
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``np.in1d`` (used by ``np.isin``) can now switch to a faster algorithm
(up to >10x faster) when it is passed two integer arrays.
This is often automatically used, but you can use ``kind="sort"`` or 
``kind="table"`` to force the old or new method, respectively.