Twenty Thirteen: minor tweaks and fixes, props obenland. Fixes #23698.

 * Add 1px to top margin for second level menus to align child menus with parent height
 * Remove text-decoration on hover for cancel-comment-reply-link
 * Pull floated images only in post content
 * Close edit link span element correctly

git-svn-id: http://core.svn.wordpress.org/trunk@23629 1a063a9b-81f0-0310-95a4-ce76da25c4cd