Merge pull request #2158 from Carreau/tuple_params

Remove tuple auto unpack in function definition 

This is for 2to3 compatibility., and also deactivate the application of 
the corresponding 2to3 fix when using python3 and setup.py.

setup.py

@@ -274,6 +274,7 @@ if 'setuptools' in sys.modules:
                 'lib2to3.fixes.fix_has_key',
                 'lib2to3.fixes.fix_next',
                 'lib2to3.fixes.fix_repr',
+                'lib2to3.fixes.fix_tuple_params',
                 ]
         from setuptools.command.build_py import build_py
         setup_args['cmdclass'] = {'build_py': record_commit_info('IPython', build_cmd=build_py)}