Refactor trip add related things from TripController into separate class, add some more complicated functionality like trip recalculation/removal

[infinifen]

The trip add method in the trip controller has honestly grown a bit too complex for my taste and I'd like to put it somewhere else along with a bunch of other overall-area-management-things. Deleting a trip, for example, requires deleting that one trip and recomputing overall area from scratch, which will essentially reuse 90% of that add trip method. yadda yadda i have to get on this