A bot to help the board with their meeting agenda and meeting
reminders.

Board members can add items to the agenda by sending a message
containing something like

```
/agenda Kaffet är slut!
```

in either Slack or Discord. The bot sends a confirmation in both Slack
and Discord so everyone can see what's added.

Every wednesday afternoon (configurable), the day before the meeting,
the bot sends a reminder in both Slack and Discord, as well as the
agenda.

More features TBD.