@mentions broken in forum

[DJPaul]

@mentions are broken in forum. They aren't being autolinked, etc.

[DJPaul]

And everywhere other than activity stream. On it.

[boonebgorges]

As usual, this ended up being more complex to fix than I wanted.

Please see 3363.diff. It reinstates @mention highlighting throughout. I have also reconfigured things so that @-mention notifications (both BP notifications and email notifications) are sent more consistently. The one remaining inconsistency is that notifications are only sent on the portion of the content that appears in the activity item itself. Thus, if you have a very long forum post, for example, with @boonebgorges at the beginning and @djpaul at the end, *both* will be linked, but only @boonebgorges will get a BP/email notification, because the activity contains just an excerpt.

I think this is acceptable, because it's an improvement over the current situation (where you only get notifications when you're mentioned in an update). But I want to get feedback before committing anything.

[DJPaul]

Sounds like a good improvement!

[boonebgorges]

(In [4738]) Fixes at-mentions so that they are turned into links in contexts other than activity updates. Fixes #3363. Deprecates groups_at_mention_notification() in favor of bp_activity_at_message_notification(). Reconfigures at-mention notification so that BP notifications and email notifications are receieved for a wider variety of activity item types.