The test is failing on one of the stable FreeBSD buildbots.  It seems
unlikely that the gc module would not be available, so switching to
_imp may not fix the problem.

I was confused by the text saying that read_events "iterated", since it
actually returns an iterator (that's what a generator does) that the
caller must then iterate.  So I tidied up the language.  I'm not sure
what the sentence "Events provided in a previous call to read_events()
will not be yielded again." is trying to convey, so I didn't try to fix that.

Also fixed a couple more news items.

Also add missing tests to test_pydoc.

Also update news entry for SMTPException; when I changed it from
IOError to OSError I forgot to update the news item.

And more news entry clarifications.

Also clarify some NEWS entries.

take two parameters.

It was discussed in issue #17460 whether or not to make the remaining
arguments keyword only so that things would fail noisily if someone was still
using positional parameters, but no decision was made and we are now well past
the Beta API change deadline.

Also rewrote the send_error description for clarity and correct English.

Patch by Christian Heimes, with modifications.