Introduce [audio] and [video] shortcodes, and use MediaElement.js to play them.

props wonderboymusic. see #23282.

git-svn-id: http://core.svn.wordpress.org/trunk@23729 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -4020,3 +4020,23 @@ $("#wp-auth-check-form iframe").load(function(){
 </script>
 </div>' ) );
 }
+
+/**
+ * Return RegEx body to liberally match an opening HTML tag that:
+ * 1. Is self-closing or
+ * 2. Has no body but has a closing tag of the same name or
+ * 3. Contains a body and a closing tag of the same name
+ *
+ * Note: this RegEx does not balance inner tags and does not attempt to produce valid HTML
+ *
+ * @since 3.6.0
+ *
+ * @param string $tag An HTML tag name. Example: 'video'
+ * @return string
+ */
+function get_tag_regex( $tag ) {
+	if ( empty( $tag ) )
+		return;
+
+	return sprintf( '(<%1$s[^>]*(?:/?>$|>[\s\S]*?</%1$s>))', tag_escape( $tag ) );
+}