[horde] New Horde Setup Tool in horde/base v6.0.0alpha15

[Ralf Lang]

>
> I ran into another issue going from imp-7.0.0alpha16 to 
> imp-7.0.0alpha17: links in emails do not open. You MUST do a 
> right-click "open in new window/tab". Is there a new/different 
> security mechanism in place?
>
> If I revert imp to alpha16, then I can click on links in emails. 
> Updating imp to alpha17 breaks that feature. I'm looking at the diffs 
> in alpha17, but not sure where to start to find that.
>
> Thanks again...working better all the ttime!
>
https://github.com/horde/imp/issues/23