[Reviewer: Rob] Add support for protocol independent (IPv4/IPv6) table indices based upon RFC 4001.

I believe this is a way to move forward from the IpAddress table indices used in the current MIB. I'm not sure it is the best way. It is more of an experiment, and a place to start the discussion of how to proceed.
That is true, the MIB changes are not backwards-compatible. Is there an appropriate place to document this other than a sprint’s release notes?