[development] For 4.8 inclusion

[Earl Miles]

Neil (and everybody who has an interest) --

I'd like to submit the na_arbitrator package, or at least the core of 
it, for merging into core. I don't think what I have is a good final 
solution, but it is a good next step in making Drupal's node_access 
behave more reliably.

And with that, I would then like to consider integrating the 
forum_access code directly into the forum module, which would make a lot 
of people very happy, though I'm on the fence as to whether it should 
actually be done.