Psaw

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* Fixed `aggs` support.
* If an aggs parameter is provided to a search method, it will be returned as the first result.
* Subsequent results will be yielded as though there was no aggs parameter.
* To the best of my understanding, PushShift only returns 100 results per agg, and there is not
way to page for additional results.

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* New parameter documentation added to README.
* Fixed bug with non-default sort.
* Fixed bug with using praw.Reddit instance with submission search.

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* Updates to README

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* Added praw support. If ``praw.Reddit`` object provided to ``PushshiftAPI``,
gets ids from pushshift and passes them to praw.
* Added support for ``/reddit/submission/comment_ids/`` endpoint.
* Added change log.

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* Improved rate limit handling
* Misc bug fixes.

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* Dirty support for ``reddit/comment/search`` and ``reddit/comment/search``.