18ecc8a78f
As we can see in (original) read code, ob pointer in groupobject is actually a 'USER_ONE' case. This was not done in 'add object to group' code, probably because we can assume objects always have at least one user in that case? Made it explicit now. Also fixed foreach_ID_link looper. In general we have waaayyyyyy too much 'own handling' of ID->us count in code currently, will clean up that...