`_doing_it_wrong()` notices are now generated when passing out-of-range values (`month=13`) or invalid dates (`2014-02-29`). Includes unit tests. Props ChriCo. Fixes #25834. git-svn-id: https://develop.svn.wordpress.org/trunk@29925 602fd350-edb4-49c9-b593-d223f7449a82