[issue30240] Add daemon keyword argument to Thread constructor

[TaoQingyun]

Changes by TaoQingyun <845767657 at qq.com>:


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versions: +Python 2.7, Python 3.3, Python 3.4, Python 3.5, Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue30240>
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