Allow user install

[Simon J. Gerraty]

On Tue, 26 Jun 2012 08:18:05 -0700, Tim Kientzle writes:
>Better idea:  have the build write a textual description of the
>tar entries.  That description can then be fed to tar to build
>the actual tarball.

Yes, that's what we do - manifest files that tar and other tools use to
produce the install images.

>The description format that tar already supports is a variant
>mtree format borrowed from NetBSD.  Each line specifies
>the tar entry fields (filename, owner, permissions, etc) and
>the filename where the file contents are stored.

Yes, we've added that support to makefs - I believe it is already in
-current.  There's still quite a bit to do.