Patch to cache overview column header images

[ftzdomino]

This patch to vtext.php will allow browsers to cache the overview title images for 24 hours, preventing the delay of having to regenerate them each time:

--- vtext.php.orig 2010-09-30 09:49:25.000000000 -0500
+++ vtext.php 2010-09-30 09:56:15.000000000 -0500
@@ -39,7 +39,10 @@
check_fields($fields);
?>
<?php
-
+
+ $offset = 3600 * 24;
+ $expire = "Expires: " . gmdate("D, d M Y H:i:s", time() + $offset) . " GMT";
+ header($expire);
$text = get_request('text', ' ');
$font = get_request('font', 9);
$color = get_request('color', 'black');