Rename 'py2exe' 'frozen'.
Don't use atomic_open on Windows.

It raises some damn PermissionErrors.
Rewrite instructions for Windows packaging.
Move GdkX11 import under the try-block.

It's not available on Windows.
Rewrite winsetup.py.
Rewrite Windows build scripts.
Use str to get error messages.

Tuple contents can vary by platform.