NEWS: structure Timing provides various operations for timing;

--- a/NEWS	Sun Mar 20 22:08:12 2011 +0100
+++ b/NEWS	Sun Mar 20 22:26:43 2011 +0100
@@ -65,6 +65,9 @@
 
 *** ML ***
 
+* Structure Timing provides various operations for timing; supersedes
+former start_timing/end_timing etc.
+
 * Path.print is the official way to show file-system paths to users
 (including quotes etc.).