[PATCH 5 of 5] template: add successors template

[Augie Fackler]

> On Jul 7, 2017, at 2:50 PM, Boris Feld <boris.feld at octobus.net> wrote:
> 
>> "successorsset" looks okay to me, since "set" and "group" are not
>> that much
>> different.
> 
> Successorgroup sound good to me, it is less implementation specific and
> might be easier to understand for users.

I think successorgroup is a bit better as well. Can someone mail a followup?