To speed up the install and upgrade schema only copy files that don't exist in the destination directory.

resources/classes/install.php

@@ -50,8 +50,10 @@ include "root.php";
 			while(false !== ($file = readdir($dir))) {
 				if (($file != '.') && ($file != '..')) {
 					if (is_dir($src.'/'.$file)) {
+						if (!file_exists($dst.'/'.$file)) {
 							$this->recursive_copy($src.'/'.$file, $dst.'/'.$file);
 						}
+					}
 					else {
 						//show debug info
 							//echo "copy(".$src."/".$file.", ".$dst."/".$file.");<br />\n";