freelists.  Changes their CompactFreeList apis into ClearFreeList apis and
  calls them via gc.collect().

_PyLong_Format.  In longobject.c, changed long_format to
_PyLong_Format.  In intobject.c, changed uses of PyOS_snprintf to
_PyInt_Format instead.

_PyLong_Format is similar to py3k's routine of the same name, except
it has 2 additional parameters: addL and newstyle.  addL was existing
in long_format, and controls adding the trailing "L".  This is
unneeded in py3k.  newstyle is used to control whether octal prepends
"0" (the pre-2.6 style), or "0o" (the 3.0 sytle).

PyNumber_ToBase is needed for PEP 3127 (Integer Literal Support and
Syntax) and PEP 3101 (Advanced String Formatting).

This changeset does not need merging into py3k.

I implemented the function sys._compact_freelists() and C API functions PyInt_/PyFloat_CompactFreeList() to compact the pre-allocated blocks of ints and floats. They allow the user to reduce the memory usage of a Python process that deals with lots of numbers.
The patch also renames sys._cleartypecache to sys._clear_type_cache

of some of the common builtin types.

Use a bit in tp_flags for each common builtin type.  Check the bit
to determine if any instance is a subclass of these common types.
The check avoids a function call and O(n) search of the base classes.
The check is done in the various Py*_Check macros rather than calling
PyType_IsSubtype().

All the bits are set in tp_flags when the type is declared
in the Objects/*object.c files because PyType_Ready() is not called
for all the types.  Should PyType_Ready() be called for all types?
If so and the change is made, the changes to the Objects/*object.c files
can be reverted (remove setting the tp_flags).  Objects/typeobject.c
would also have to be modified to add conditions
for Py*_CheckExact() in addition to each the PyType_IsSubtype check.

exposed in header files.  Fixed a few comments in these headers.

As we might have expected, writing down invariants systematically exposed a
(minor) bug.  In this case, function objects have a writeable func_code
attribute, which could be set to code objects with the wrong number of
free variables.  Calling the resulting function segfaulted the interpreter.
Added a corresponding test.

New functions:
  unsigned long PyInt_AsUnsignedLongMask(PyObject *);
  unsigned PY_LONG_LONG) PyInt_AsUnsignedLongLongMask(PyObject *);
  unsigned long PyLong_AsUnsignedLongMask(PyObject *);
  unsigned PY_LONG_LONG) PyLong_AsUnsignedLongLongMask(PyObject *);

New and changed format codes:

b unsigned char 0..UCHAR_MAX
B unsigned char none **
h unsigned short 0..USHRT_MAX
H unsigned short none **
i int INT_MIN..INT_MAX
I * unsigned int 0..UINT_MAX
l long LONG_MIN..LONG_MAX
k * unsigned long none
L long long LLONG_MIN..LLONG_MAX
K * unsigned long long none

Notes:

* New format codes.

** Changed from previous "range-and-a-half" to "none"; the
range-and-a-half checking wasn't particularly useful.

New test test_getargs2.py, to verify all this.

functions are here.  Suggested by Skip.