(ITS#5330) back-null upgrade

Full_Name: Hallvard B Furuseth Version: HEAD OS: URL: Submission from: (NULL) (129.240.6.233) Submitted by: hallvard

I'll be upgrading back-null a bit. At the moment just support for Back-config, Modify-Increment Extension and empty rootpw.

Maybe grow it to a useful template of a nontrivial backend later (after I learn how to write that), with access control, referrals, various extensions... Might be almost-unused and thus subject to code rot, but less so than documentation of the backend API.

However I imagine that could slow it down somewhat, so it might become less useful when used to benchmark backends. (E.g. if you run a test with some backend, then with back-null, diff the time to see how much was spent in the backend.)