SF bug #681003: itertools issues

* Fixed typo in exception message for times()
* Filled in missing times_traverse()
* Document reasons that imap() did not adopt a None fill-in feature
* Document that count(sys.maxint) will wrap-around on overflow
* Add overflow test to islice()
* Check that starmap()'s argument returns a tuple
* Verify that imap()'s tuple re-use is safe
* Make a similar tuple re-use (with safety check) for izip()

Doc/lib/libitertools.tex

@@ -82,6 +82,10 @@ by functions or loops that truncate the stream.
              yield cnt
              cnt += 1
   \end{verbatim}
+
+  Note, \function{count()} does not check for overflow and will return
+  negative numbers after exceeding \code{sys.maxint}.  This behavior
+  may change in the future.
 \end{funcdesc}
 
 \begin{funcdesc}{dropwhile}{predicate, iterable}