[horde] horde_hook_postauthenticate called after logout

[Chuck Hagenbuch]

Quoting Michael Menge <michael.menge at zdv.uni-tuebingen.de>:

> Sorry, but the patch didn't help. It seams to me every action of imp  
> is triggering the hook. Can i help with some more infomations to  
> debug/reproduce the bug?

So, the postauthenticate hook is meant to be called whenever  
Auth::authenticate is called, and it's meant to have a chance to deny  
access whenever that method is called. We can't call the hook just on  
logins, and the way IMP's authentication works, we call up to the  
parent authenticate() method to verify credentials on each page.

For your purposes, _imp_hook_postlogin might be better. I'd also be  
fine with adding a postlogin hook to Horde itself for more general use.

Sorry for the confusion,
-chuck