Added pickle support for third-party BitGenerators
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The pickle format for bit generators was extended to allow each bit generator
to supply its own constructor when during pickling. Previous  versions of NumPy
only supported unpickling ``Generator`` instances created with one of the core set
of bit generators supplied with NumPy. Attempting to unpickle a ``Generator``
that used a third-party bit generators would fail since the constructor used during
the unpickling was only aware of the bit generators included in NumPy.


Add a release note for bit generator reduce changes
DOC: Add a release note for bit generator reduce changes

Add a release note highlighting that Generators now support
pickling and unpickling using third party bit-generators
