[horde] share sql driver and bitwise operations

[Chuck Hagenbuch]

Quoting Michael Rubinsky <mrubinsk at horde.org>:

> I agree this is a good idea, provided the speed gained from the  
> faster  queries isn't lost in merging the results in PHP.

We _could_ still do it all as a join while still reorganizing the  
tables to avoid bitwise operations. MySQL especially though seems to  
benefit from having queries broken up for it.

> The only issue/concern that comes to mind is how would we handle   
> "custom" perms. For instance, in Kronolith we use a PERMS_DELEGATE   
> constant.

Since we have per-app (or really we should start thinking about and  
naming these as per-share) tables now, we could just add that column  
to the Kronolith share tables, and extend the Perms_sql code to know  
about custom permissions and check for them (add a new perm to the  
standard set).

-chuck