[dev] Group hooks patch

[Chuck Hagenbuch]

Quoting Jason Rust <jrust at rustyparts.com>:

> Finally getting around to finishing up the hooks driver for Groups.
> Attached is a patch which cleans up a couple bugs in the driver, adds an
> example hook to hooks.php.dist, adds a group driver option to
> conf.php.dist, and patches Group::singleton() to check for that driver.

Committed, thanks.

-chuck

--
Charles Hagenbuch, <chuck at horde.org>
"I'm really... I'm not too fascinated by green food." - Average Joe