fix rnids - follow up

[oschulte]

get rid of the annoying fake rnids

1. Make LatticeMember output orig_rnid as well as rnid.
2. Replace rnid with orig_rnid in metadata script.
3. Drop rnid.
4. Make view Mapping where 1-length Rchains map to their LatticeMembers.

[oschulte]

Also

1. check that BN learning still works
2. rewrite BIF generator (no longer needs to map rnids)
3. Check that MLN generator still works