Update to PHPMailer 5.2.4. props bpetty. fixes #21074.



git-svn-id: http://core.svn.wordpress.org/trunk@23522 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: usability improvement for better viewing of images on attachment pages. Props DrewAPicture and obenland, fixes #23543. 

git-svn-id: http://core.svn.wordpress.org/trunk@23523 1a063a9b-81f0-0310-95a4-ce76da25c4cd