Added the --expand [ or --pushback or --merge ] options.

--expand is a bit confusing to remember for some reason.  and merge
could conflict with git thinking... pushback makes the most sense.
Modified option to read --push-from.

Also modified the --freeze option to not modify stuff in the
chosen directory.

The --freeze option can be a LOT smarter.  Like actually checking
the manifest for what you want to merge.