Remove [PATCH] prefixes

They get in the way of the interdiff in the case of reordering.
Improve print order and verbosity

Try to order by the RHS, since we assume that the user is looking at
that as the "new" version.  Insert "removed" (LHS-only) commits once
we have shown all the other commits that came before them on the LHS.
That way the LHS is in order "as far as it can be done".
Support colored output

Vaguely the same as diff coloring, but it also colors the commit lines
themselves if the commit as a whole is new or removed.