Move test_tokenize to doctest.

Done as GHOP 238 by Josip Dzolonga.
diff --git a/Misc/NEWS b/Misc/NEWS
index e316c13..539b785 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -50,6 +50,8 @@
 Tests
 -----
 
+- GHOP 238: Convert test_tokenize to use doctest.
+
 - GHOP 237: Rewrite test_thread using unittest.
 
 - Patch #2232: os.tmpfile might fail on Windows if the user has no