expanded philsturgeon's bugfix to parse_url() and updated docs and changelog
diff --git a/system/helpers/url_helper.php b/system/helpers/url_helper.php
index 86caa27..7707d68 100644
--- a/system/helpers/url_helper.php
+++ b/system/helpers/url_helper.php
@@ -431,7 +431,7 @@
 /**
  * Prep URL
  *
- * Simply adds the http:// part if missing
+ * Simply adds the http:// part if no scheme is included
  *
  * @access	public
  * @param	string	the URL
@@ -446,7 +446,7 @@
 			return '';
 		}
 
-		if (!preg_match('/^[a-z]{3,6}:\/\//', $str))
+		if ( ! parse_url($str, PHP_URL_SCHEME))
 		{
 			$str = 'http://'.$str;
 		}