Highlights:
 - Adding PyObject_Format.
 - Adding string.Format class.
 - Adding __format__ for str, unicode, int, long, float, datetime.
 - Adding builtin format.
 - Adding ''.format and u''.format.
 - str/unicode fixups for formatters.

The files in Objects/stringlib that implement PEP 3101 (stringdefs.h,
unicodedefs.h, formatter.h, string_format.h) are identical in trunk
and py3k.  Any changes from here on should be made to trunk, and
changes will propogate to py3k).

type.__new__(), and then calls object.__init__(cls), just to be anal.

This allows us to restore the code in string.py's _TemplateMetaclass
that called super(...).__init__(name, bases, dct), which I commented
out yesterday since it broke due to the stricter argument checking
added to object.__init__().

  now stricter in rejecting excess arguments.  The only time when
  either allows excess arguments is when it is not overridden and the
  other one is.  For backwards compatibility, when both are
  overridden, it is a deprecation warning (for now; maybe a Py3k
  warning later).

When merging this into 3.0, the warnings should become errors.

Note: without the change to string.py, lots of spurious warnings happen.
What's going on there?

str() or repr()) would work, just not multi-value tuples. Probably not a
backport candidate, since it changes the behaviour of passing a
single-element tuple:

>>> string.Template("$foo").substitute(dict(foo=(1,)))

'(1,)'

versus

'1'