Have installer create script-output shortcut

[JasonC]

When I first installed blueprint string I had a little bit of trouble locating the referenced "script-output" directory. I also saw a decent number of posts by other new users also looking for this when I was first looking around.

Currently, at least on Windows, the installer creates a shortcut to the user-specific mods and saves directories.

I think it would be helpful if it also created a shortcut to script-output there.

This would also make it easier to tell new users where to find it when they ask. Assuming symbolic links are created on *nix and something similar is done on OS X, users can be pointed to the common Factorio installation directory on any system instead of e.g. wherever the user data path du jour is on Windows.