Tidy up references to ipclusterz in parallel examples.

docs/examples/parallel/plotting/plotting_frontend.py

@@ -5,7 +5,7 b' The two files plotting_frontend.py and plotting_backend.py go together.'
 To run this example, first start the IPython controller and 4
 engines::
 
-    ipclusterz start -n 4
+    ipcluster start -n 4
 
 Then start ipython in pylab mode::
 

docs/examples/parallel/task_profiler.py

@@ -6,7 +6,7 b' are basically just a time.sleep(t), where t is a random number between'
 two limits that can be configured at the command line.  To run
 the script there must first be an IPython controller and engines running::
 
-    ipclusterz start -n 16
+    ipcluster start -n 16
 
 A good test to run with 16 engines is::