It started exporting a isSymbolicLink which supports windows. But,
git-annex does no use symlinks on windows yet and this conflicts with the
function by the same name from unix-compat, so hide it.
Also automated downloading the builds, finally. I had done it by hand until
now.
Note that the Windows autobuilder has an expired cert, so it will refuse to
download from it currently. I have emailed its admin to get that fixed,
hopefully.
This commit was sponsored by Peter Hogg.
