round included:
 * Revert round to its 2.6 behavior (half away from 0).
 * Because round, floor, and ceil always return float again, it's no
   longer necessary to have them delegate to __xxx___, so I've ripped
   that out of their implementations and the Real ABC. This also helps
   in implementing types that work in both 2.6 and 3.0: you return int
   from the __xxx__ methods, and let it get enabled by the version
   upgrade.
 * Make pow(-1, .5) raise a ValueError again.

and adds errors for -0x.

directory permissions and times.

(will backport to 2.5)

compatibility after r59671 made them return integral types.

* Make the _replace() method respect subclassing.

* Using property() to make _fields read-only wasn't a good idea.
  It caused len(Point._fields) to fail.

* Add note to _cast() about length checking and alternative with the star-operator.

On Windows, when import fails to load a dll module, the message says
"error code 193" instead of a more informative text.

It turns out that FormatMessage needs additional parameters for some error codes.
For example: 193 means "%1 is not a valid Win32 application".
Since it is impossible to know which parameter to pass, we use
FORMAT_MESSAGE_IGNORE_INSERTS to get the raw message, which is still better
than the number.

Modified PyImport_Import and PyImport_ImportModule to always use absolute imports by calling __import__ with an explicit level of 0
Added a new API function PyImport_ImportModuleNoBlock. It solves the problem with dead locks when mixing threads and imports