[PATCH 0 of 7] Port of hg's modules to py3k, round two

[Renato Cunha]

Hello again,

for this third iteration, after chatting in IRC with some people, I decided
for using the PyBytes_* API defined in 2.6+ and backport it for Python <= 2.5.
There are also some other 2.6 backports, inspired by Michael Tharp's (rPath)
code.

This patch series also builds on the results of testing on Windows, which
includes the changes in osutils.c's posixfile. This last version was tested in
windows with python 2.6 & 3.1 and in Linux with Python 2.4, 2.6 and 3.1. By
"tested" I mean "built and with modules successfully included". The tests
aren't comprehensive, but should be enough to ensure that the behavior in 2.x
is preserved and that it is at least buildable in 3.x (I'm not really
considering 3.0 here).

As always, any comments are welcome.