The `notify_moderator` filter makes it possible to override the value for the `moderation_notify` option, which controls whether to send new comment emails to "site moderators", that is to say, the owner of the admin email for the site and the post author if they have the ability to modify the comment.
The `notify_post_author` filter likewise makes it possible to override the value for the `comments_notify` option, which controls whether to send new comment emails to the post author. If the post author is the comment author, default behavior is not to send the notification. Note: enabling or disabling notifications via this hook could also affect other recipients added via the 'comment_notification_recipients' filter in `wp_notify_postauthor()`, if hooked.
Passing a falsey value to either of the new filters will prevent notifications from being sent, regardless of their corresponding option values.
Adds tests.
Props coffee2code, adamsilverstein, DrewAPicture.
Fixes#761.
git-svn-id: https://develop.svn.wordpress.org/trunk@35339 602fd350-edb4-49c9-b593-d223f7449a82