shorten the integrate test

Demos/integrate_timing.py

@@ -8,7 +8,7 @@ number = 10
 py_time = None
 for m in ('integrate0', 'integrate1', 'integrate2'):
     print(m)
-    t = min(timeit.repeat("integrate_f(0.0, 10.0, 10000000)", "from %s import integrate_f" % m, number=number))
+    t = min(timeit.repeat("integrate_f(0.0, 10.0, 100000)", "from %s import integrate_f" % m, number=number))
     if py_time is None:
         py_time = t
     print("    ", t / number, "s")