[ci skip] Fix comment typos

https://github.com/bcit-ci/CodeIgniter/pull/3748#issuecomment-90925762
diff --git a/system/core/Router.php b/system/core/Router.php
index eb3da22..f91d3f6 100644
--- a/system/core/Router.php
+++ b/system/core/Router.php
@@ -493,7 +493,7 @@
 	 * Set directory name
 	 *
 	 * @param	string	$dir	Directory name
-	 * @param	bool	$appent	Whether we're appending rather then setting the full value
+	 * @param	bool	$appent	Whether we're appending rather than setting the full value
 	 * @return	void
 	 */
 	public function set_directory($dir, $append = FALSE)
diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 5005d01..8251f45 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -2255,7 +2255,7 @@
 			else
 			{
 				// Cycle through the "select" portion of the query and prep each column name.
-				// The reason we protect identifiers here rather then in the select() function
+				// The reason we protect identifiers here rather than in the select() function
 				// is because until the user calls the from() function we don't know if there are aliases
 				foreach ($this->qb_select as $key => $val)
 				{