!alarm allow alarms for groups.

[Jwaxo]

Quoted from #45 from @anniegreens:
"It would be nice for this to also include functionality to !alert a @group. For example reminding @lunch to go to Boke Bowl tomorrow. Though by the time this is done, that last sentence will be moot."

[Jwaxo]

We now have functionality for group functions that extend outside of the groups plugin, so this should be easy to implement.

[purplexa]

Maybe we should rework the group stuff so the bot just passes group stuff back through, although that would require a proper architecture to even be possible.

[Jwaxo]

Yeah, it occurred to me, but I couldn't think of a way to do it without completely reworking how the "analyze input" works.