Sun, 20 May 2018 20:14:30 +0100 paulson one last fix
Sun, 20 May 2018 18:37:34 +0100 paulson tidy up of Derivative
Sun, 20 May 2018 22:04:46 +0200 wenzelm avoid undeclared frees;
(0) -30000 -10000 -3000 -1000 -300 -100 -30 -10 -3 +3 +10 +30 +100 +300 +1000 +3000 +10000 tip