Start of early patch applicator tools for git.

Start of early patch applicator tools for git.

I looked a bit at my old BK tools for the same thing, but they were
just so horrid in many ways that I largely rewrote it all and these
tools do things a bit differently. Instead of aggressively piping
data from one process to another (which was clever but very hard
to follow), this first just splits out the mbox into many smaller
email files, and then does some scripts on these temporary files.