Backport of several functions from Python 3.0 to 2.6 including PyUnicode_FromString, PyUnicode_Format and PyLong_From/AsSsize_t. The functions are partly required for the backport of the bytearray type and _fileio module. They should also make it easier to port C to 3.0.
First chapter of the Python 3.0 io framework back port: _fileio
The next step depends on a working bytearray type which itself depends on a backport of the nwe buffer API.

This checkin is adapted from part 2 (of 3) of Trevor Perrin's patch set.

BACKWARD INCOMPATIBILITY:  SHIFT must now be divisible by 5.  AFAIK,
nobody will care.  long_pow() could be complicated to worm around that,
if necessary.

long_pow():
  - BUGFIX:  This leaked the base and power when the power was negative
    (and so the computation delegated to float pow).
  - Instead of doing right-to-left exponentiation, do left-to-right.  This
    is more efficient for small bases, which is the common case.
  - In addition, if the exponent is large (more than FIVEARY_CUTOFF
    digits), precompute [a**i % c for i in range(32)], and go left to
    right 5 bits at a time.
l_divmod():
  - The signature changed so that callers who don't want the quotient,
    or don't want the remainder, can pass NULL in the slot they don't
    want.  This saves them from having to declare a vrbl for unwanted
    stuff, and remembering to decref it.
long_mod(), long_div(), long_classic_div():
  - Adjust to new l_divmod() signature, and simplified as a result.

This checkin is adapted from part 1 (of 3) of Trevor Perrin's patch set.

x_mul()
  - sped a little by optimizing the C
  - sped a lot (~2X) if it's doing a square; note that long_pow() squares
    often
k_mul()
  - more cache-friendly now if it's doing a square
KARATSUBA_CUTOFF
  - boosted; gradeschool mult is quicker now, and it may have been too low
    for many platforms anyway
KARATSUBA_SQUARE_CUTOFF
  - new
  - since x_mul is a lot faster at squaring now, the point at which
    Karatsuba pays for squaring is much higher than for general mult

Thanks to Skip Montanaro and Kalle Svensson for the patches.

instead of faking it by hand.  It *is* a var object, and nothing but
hysterical raisins to pretend it's an oddball.

Given an immutable type M, and an instance I of a subclass of M, the
constructor call M(I) was just returning I as-is; but it should return a
new instance of M.  This fixes it for M in {int, long}.  Strings, floats
and tuples remain to be done.
Added new macros PyInt_CheckExact and PyLong_CheckExact, to more easily
distinguish between "is" and "is a" (i.e., only an int passes
PyInt_CheckExact, while any sublass of int passes PyInt_Check).
Added private API function _PyLong_Copy.

This should match the situation in the 1.6b1 tree.

comments, docstrings or error messages. I fixed two minor things in
test_winreg.py ("didn't" -> "Didn't" and "Didnt" -> "Didn't").

There is a minor style issue involved: Guido seems to have preferred English
grammar (behaviour, honour) in a couple places. This patch changes that to
American, which is the more prominent style in the source. I prefer English
myself, so if English is preferred, I'd be happy to supply a patch myself ;)

This was a convenient excuse to create the pyport.h file recently
discussed!
Please use new Py_ARITHMETIC_RIGHT_SHIFT when right-shifting a
signed int and you *need* sign-extension.  This is #define'd in
pyport.h, keying off new config symbol SIGNED_RIGHT_SHIFT_ZERO_FILLS.
If you're running on a platform that needs that symbol #define'd,
the std tests never would have worked for you (in particular,
at least test_long would have failed).
The autoconfig stuff got added to Python after my Unix days, so
I don't know how that works.  Would someone please look into doing
& testing an auto-config of the SIGNED_RIGHT_SHIFT_ZERO_FILLS
symbol?  It needs to be defined if & only if, e.g., (-1) >> 3 is
not -1.

rid of Py_PROTO, switched to ANSI function decls, and did some
minor fiddling.

use the new names exclusively, and the linker will see the new names.
Files that import "Python.h" also only see the new names.  Files that
import "allobjects.h" will continue to be able to use the old names,
due to the inclusion (in allobjects.h) of "rename2.h".

object.h: made sizes and refcnts signed ints.
stringobject.h: make getstrsize() signed int.
methodobject.h: add METH_VARARGS and METH_FREENAME flag bit definitions.

* Makefile: change location of FORMS library.
* posixmodule.c: turn #if 0 into #ifdef MSDOS (stuff in unistd.h or not)
* Almost all .h files: added CPP magic to avoid duplicate inclusions and
  to support inclusion from C++.

* Stubs for faster implementation of local variables (not yet finished)
* Added function name to code object.  Print it for code and function
  objects.  THIS MAKES THE .PYC FILE FORMAT INCOMPATIBLE (the version
  number has changed accordingly)
* Print address of self for built-in methods
* New internal functions getattro and setattro (getattr/setattr with
  string object arg)
* Replaced "dictobject" with more powerful "mappingobject"
* New per-type functio tp_hash to implement arbitrary object hashing,
  and hashobject() to interface to it
* Added built-in functions hash(v) and hasattr(v, 'name')
* classobject: made some functions static that accidentally weren't;
  added __hash__ special instance method to implement hash()
* Added proper comparison for built-in methods and functions

Remove some functions that need not be exported.