Win32 binding replacement

[Andrej Mitrovic]

Maybe we could solve this via version statements. Esentially:

version(WinAPI)
{
   import win32.winbase; // or whatever module
}
else
{
    import core.sys.windows.windows;
}

Then again I think this could mean Phobos would have to be recompiled
if you added version=WinAPI to your command line.

Replacing the Phobos Windows bindings could also be an option. The
dsource bindings are 2.5 megs in size, but this wouldn't be much of an
issue if we properly separated DMD zip packages. Fo for example we
wouldn't have linux/freebsd/osx folders in the windows DMD package.
Just removing those folders frees up 46 megs.