Add constant to allow disabling group auto join [HAS-PATCH]

[boonebgorges]

When a non-member of a public group posts to that group's forum, they're auto-joined. Until such a time when and if BP forums are rewritten, it'd be nice to have an action hook that could be used to reverse this process. Should be quite harmless, so I hope it can get put into 1.2.6.

[DJPaul]

RE: http://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/time-sensitive-how-to-prevent-auto-join-for-a-forumgroup-1/

groups_join_group happens first and then the patch/bp-custom.php calls groups_leave_group after. This feels a bit hackish as you're sending another database query (and essentially wasting the first one). However, I can't see any negative consequence with this patch as it'd be up to individual site admins to add code to call groups_leave_group if they wanted to do that.

[boonebgorges]

Good call, Paul.

I probably should have slept on this one. I didn't look into how group forum posting worked, assuming that it would require a lot of messing around to remove the group membership requirement on forum posting. But there isn't really any, from the individual member point of view.

The second patch (disable_auto_join_constant.patch) does it the right way and avoids the extra queries.

[r-a-y]

Second patch is much cleaner ;)

[johnjamesjacoby]

(In [3178]) Fixes #2540 props boonebgorges