Finish code snippet for timings

doc/source/user_guide/numpy_images.txt

@@ -170,3 +170,12 @@ in a different order, even if the number of operations is the same:
     ...         arr[:, :, frame] *= scalar
     ... 
     >>> import time
+    >>> im3d = np.random.rand(100, 1024, 1024)
+    >>> t0 = time.time(); x = in_order_multiply(im3d, 5); t1 = time.time()
+    >>> print(t1 - t0, "seconds")
+    >>> im3d_t = np.transpose(im3d).copy()
+    >>> im3d_t.shape
+    (1024, 1024, 100)
+    >>> s0 = time.time(); x = out_of_order_multiply(im3d, 5); s1 = time.time()
+    >>> print(s1 - s0, "seconds")
+    >>> print("Speedup: ", (s1 - s0) / (t1 - t0))