shell32: symlink user's profile shell folders to xdg well known directories [2/2] (try 3)

[Dan Kegel]

I feel like a broken record, but:
some apps don't like following symlinks, and the
native Windows way to configure what the "My Foo"
folders point to is called shell folder redirection;
These are documented at
http://support.microsoft.com/kb/242557
among other places, and I think Wine supports these
registry settings.  Is there any reason we don't want
to use these instead of symlinks?
- Dan