[dev] Split DataTree tables by group_uid and flatten attribute tables

[Duck]

Hi Ben, I see you uploaded your patch. I would like to go forward and combine 
our efforts, but before I have one question.

Even as I made the patch as an new DT extension I didn't mean it. I did it 
like this only for easiest testing and cleaner comparison. Now  I will extend 
the normal SQL driver to have out additional functionalists.

I see you trick DT settings in the general horde config, in my opinion we
should put this config options in the API config. Because is an API level
possibility and if we introduce the two new config option, with let say 5 
modules installed we would have 10 more config array elements in the general 
config.

Duck