The pywin32 package is no longer needed.
ctypes is now required for running Mercurial on Windows.
ctypes is included in Python since version 2.5. For Python 2.4, ctypes is
available as an extra installer package for Windows.
Moved spawndetached() from windows.py to win32.py and fixed it, using
ctypes as well. spawndetached was defunct with Python 2.6.6 because Python
removed their undocumented subprocess.CreateProcess. This fixes
'hg serve -d' on Windows.
--bundle 3 leaves all of the compiled C extensions and other DLLs outside of
the library.zip, so we no longer add the installer folder to the system PATH.
Instead, we now ship a small bin/hg.cmd and it is placed in the PATH.
Switching to py2exe --bundle 3 is necessary because the higher bundle options
are not supported on x64.
