Add Cache-Control: immutable to static files

adminer/file.inc.php

@@ -6,6 +6,7 @@ if ($_SERVER["HTTP_IF_MODIFIED_SINCE"]) {
 
 header("Expires: " . gmdate("D, d M Y H:i:s", time() + 365*24*60*60) . " GMT");
 header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
+header("Cache-Control: immutable");
 
 if ($_GET["file"] == "favicon.ico") {
 	header("Content-Type: image/x-icon");

changes.txt

@@ -1,6 +1,7 @@
 Adminer 4.2.6-dev:
 Add accessibility labels to Create Table fields
 Make maxlength in edit fields a soft limit
+Add Cache-Control: immutable to static files
 
 Adminer 4.2.5 (released 2016-06-01):
 Fix remote execution in SQLite query