Implementation of PEP 3101, Advanced String Formatting.

Known issues:

The string.Formatter class, as discussed in the PEP, is incomplete.

Error handling needs to conform to the PEP.

Need to fix this warning that I introduced in Python/formatter_unicode.c:
Objects/stringlib/unicodedefs.h:26: warning: `STRINGLIB_CMP' defined but not used

Need to make sure sign formatting is correct, more tests needed.

Need to remove '()' sign formatting, left over from an earlier version of the PEP.

Objects/longobject.c

@@ -5,6 +5,8 @@
 #include "Python.h"
 #include "longintrepr.h"
 
+#include "formatter_unicode.h"
+
 #include <ctype.h>
 
 long
@@ -3592,6 +3594,16 @@ long_getN(PyLongObject *v, void *context) {
 	return PyLong_FromLong((intptr_t)context);
 }
 
+static PyObject *
+long__format__(PyObject *self, PyObject *args)
+{
+    /* when back porting this to 2.6, check type of the format_spec
+       and call either unicode_long__format__ or
+       string_long__format__ */
+    return unicode_long__format__(self, args);
+}
+
+
 static PyObject *
 long_round(PyObject *self, PyObject *args)
 {
@@ -3632,6 +3644,7 @@ static PyMethodDef long_methods[] = {
          "Rounding an Integral returns itself.\n"
 	 "Rounding with an ndigits arguments defers to float.__round__."},
 	{"__getnewargs__",	(PyCFunction)long_getnewargs,	METH_NOARGS},
+        {"__format__", (PyCFunction)long__format__, METH_VARARGS},
 	{NULL,		NULL}		/* sentinel */
 };