Update NEWS, docs, and patchlevel for 3.7.0b2

Include/patchlevel.h

Lib/pydoc_data/topics.py

Misc/NEWS.d/3.7.0b2.rst

...EWS.d/next/Build/2018-02-21-12-46-00.bpo-32898.M15bZh.rst

...ore and Builtins/2018-01-26-21-20-21.bpo-32583.Fh3fau.rst

...ore and Builtins/2018-01-29-14-36-37.bpo-32711.8hQFJP.rst

...ore and Builtins/2018-02-01-10-16-28.bpo-32303.VsvhSl.rst

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...ore and Builtins/2018-02-02-08-50-46.bpo-31356.MNwUOQ.rst

...ore and Builtins/2018-02-20-21-53-48.bpo-32889.J6eWy5.rst

...xt/Documentation/2018-01-25-14-23-12.bpo-31972.w1m_8r.rst

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...ext/Documentation/2018-02-03-06-11-37.bpo-8722.MPyVyj.rst

...xt/Documentation/2018-02-10-12-48-38.bpo-11015.-gUf34.rst

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...xt/Documentation/2018-02-25-16-33-35.bpo-28124._uzkgq.rst

...NEWS.d/next/IDLE/2018-02-04-17-52-54.bpo-32765.qm0eCu.rst

...NEWS.d/next/IDLE/2018-02-12-11-05-22.bpo-32826.IxNZrk.rst