2016-11-08: save figure instead of showing it (for timing tests)

save figure instead of showing it (for timing tests)

diff --git a/examples/ensemble-estimation.w b/examples/ensemble-estimation.w
--- a/examples/ensemble-estimation.w
+++ b/examples/ensemble-estimation.w
@@ -340,6 +340,6 @@ scalarMap = mpl.cm.ScalarMappable(norm=c
         format port "pl.xlabel('position [arbitrary units]')\n"
         format port "pl.ylabel('value [arbitrary units]')\n"
         format port "pl.title('ensemble optimization results')\n"
-        format port "pl.show()\n"
+        format port "pl.savefig('/tmp/fit.pdf')\n"
         format port "exit()\n"
         close-pipe port