Added the cProfile module.

Based on lsprof (patch #1212837) by Brett Rosen and Ted Czotter.
With further editing by Michael Hudson and myself.
History in svn repo: http://codespeak.net/svn/user/arigo/hack/misc/lsprof

* Module/_lsprof.c is the internal C module, Lib/cProfile.py a wrapper.
* pstats.py updated to display cProfile's caller/callee timings if available.
* setup.py and NEWS updated.
* documentation updates in the profiler section:
   - explain the differences between the three profilers that we have now
   - profile and cProfile can use a unified documentation, like (c)Pickle
   - mention that hotshot is "for specialized usage" now
   - removed references to the "old profiler" that no longer exists
* test updates:
   - extended test_profile to cover delicate cases like recursion
   - added tests for the caller/callee displays
   - added test_cProfile, performing the same tests for cProfile
* TO-DO:
   - cProfile gives a nicer name to built-in, particularly built-in methods,
     which could be backported to profile.
   - not tested on Windows recently!

Doc/lib/libhotshot.tex

@@ -14,6 +14,17 @@ Hotshot is a replacement for the existing \refmodule{profile} module. As it's
 written mostly in C, it should result in a much smaller performance impact
 than the existing \refmodule{profile} module.
 
+\begin{notice}[note]
+  The \module{hotshot} module focuses on minimizing the overhead
+  while profiling, at the expense of long data post-processing times.
+  For common usages it is recommended to use \module{cProfile} instead.
+  \module{hotshot} is not maintained and might be removed from the
+  standard library in the future.
+\end{notice}
+
+\versionchanged[the results should be more meaningful than in the
+past: the timing core contained a critical bug]{2.5}
+
 \begin{notice}[warning]
   The \module{hotshot} profiler does not yet work well with threads.
   It is useful to use an unthreaded script to run the profiler over