dumpstat

This is still a WIP. It's approaching its final form, but it
could use documentation, and might need some tweaks as more
users are added.
dumpstat to fd

Like file, but probably more useful if you are a UI trying
to stream.
dumpstat-ify upload-pack
zeromq dumpstat implementation

This tries to do as little as possible on top of zeromq,
which might not work. It sends an "id" field with each
message to keep some state. Probably this should be
inherited through the environment.