Automatically add user-submitted sessions & BoFs to their personalised schedule

So you never accidentally double-book yourself

- Approved & published session nodes should automatically be added to one's personal schedule
- User submitted BoFs also appear on their personal schedule

If both content types are using the same timeslots, then it also seems idea that you won't be able to submit a BoF when you're scheduled to present however an easier option might be just to show titles + room/timeslot scheduled.

Obv, there will be exceptions, like when a site admin is submitting content on behalf of others (reassign author?).