Use sys.platform instead of os.name to detect Windows in asyncio docs. Patch by Akira Li. (Merge 3.5->3.6)

Use sys.platform instead of os.name to detect Windows in asyncio docs. Patch by Akira Li. (Merge 3.4->3.5)

Issue #24379:  Revert the operator.subscript patch (dccc4e63aef5) pending resolution of the related refcnt leak.

This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
or edited some other way to fix the grammar.

instead of optparse.

at the end if the FileInput was opened with binary mode.
Patch by Ryosuke Ito.

at the end if the FileInput was opened with binary mode.
Patch by Ryosuke Ito.

at the end if the FileInput was opened with binary mode.
Patch by Ryosuke Ito.

garbage collected.

garbage collected.