Moved a python code snippet into the examples directory from "basic tutorial".

docs/examples/tutorial/cython_tutorial/primes.py

-
-def primes(kmax):
-    result = []
-    if kmax > 1000:
-        kmax = 1000
-
-    p = [0] * 1000
-    k = 0
-    n = 2
-    while k < kmax:
-        i = 0
-        while i < k and n % p[i] != 0:
-            i += 1
-        if i == k:
-            p[k] = n
-            k += 1
-            result.append(n)
-        n += 1
-    return result

docs/examples/tutorial/cython_tutorial/primes_python.py

+def primes_python(nb_primes):
+    p = []
+    n = 2
+    while len(p) < nb_primes:
+        # Is n prime?
+        for i in p:
+            if n % i == 0:
+                break
+
+        # If no break occurred in the loop
+        else:
+            p.append(n)
+        n += 1
+    return p

docs/src/tutorial/cython_tutorial.rst

@@ -263,23 +263,9 @@ just like Python does. You can deactivate those checks by using the
 :ref:`compiler directives<compiler-directives>`.
 
 Now let's see if, even if we have division checks, we obtained a boost in speed.
-Let's write the same program, but Python-style::
-
-    def primes_python(nb_primes):
-        p = []
-        n = 2
-        while len(p) < nb_primes:
-            # Is n prime?
-            for i in p:
-                if n % i == 0:
-                    break
-
-            # If no break occurred in the loop
-            else:
-                p.append(n)
-            n += 1
-        return p
+Let's write the same program, but Python-style:
 
+.. literalinclude:: ../../examples/tutorial/cython_tutorial/primes_python.py
 
 It is also possible to take a plain ``.py`` file and to compile it with Cython.
 Let's take ``primes_python``, change the function name to ``primes_python_compiled`` and