added session cookie lifetime, modified installer accordingly

index.php

@@ -12,6 +12,7 @@
     }
     require_once ( 'functions.php' );
     $config = load_config ( );
+    session_set_cookie_params ( 43200, $config [ 'installation_path' ], $config [ 'domain' ], true );
     if ( isset ( $request_uri [ 0 ] ) && $request_uri [ 0 ] != "" ) {
         switch ( $request_uri [ 0 ] ) {
             case "go":