Merge pull request #1298 from zivyuan/patch-1

Cookie $index should start with a prefix.
diff --git a/system/core/Input.php b/system/core/Input.php
index fc2a550..7594a2e 100755
--- a/system/core/Input.php
+++ b/system/core/Input.php
@@ -226,6 +226,7 @@
 	 */
 	public function cookie($index = '', $xss_clean = FALSE)
 	{
+		$index = config_item('cookie_prefix').$index;
 		return $this->_fetch_from_array($_COOKIE, $index, $xss_clean);
 	}