Show upcoming arrivals on stations

[elliottwilliams]

The table view cell UI for stations should be changed to include badges of the routes arriving at that station. The routes are listed in order of their arrival time, and are reordered dynamically as vehicles arrive and depart.

[elliottwilliams]

Broken down into subtasks, this should entail:

• Create an ArrivalsCollectionViewController class.
• Genericize the data source from ArrivalsTableViewController into ArrivalDataSource. It should serve ArrivalsCollectionViewController as well. Note that unlike the approach in RoutesCollectionViewModel, it cannot be the delegate, as the arrivals table and arrivals collection load different nibs and represent the data differently.
• Edit station table view cell prototypes to include arrivals collections. Set custom height appropriately.

It may be necessary for performance reasons to not load arrivals for all stations of a route at once. Suggestions include:

• Ensure station bindings are closed when the station is offscreen.
• Avoid calling meta_update on models used to construct the table, and rely on vehicle_update events to populate the information. Note that this would require model-level changes.
  • By using the LastEventCache on the default Connection, the cost of redundant meta_update calls is trivialized.
• Design the arrivals table view UI to only show arrivals for one or two stations. Perhaps a couple stations scrolled near the center of the page could expand to show arrivals, or the stations would have to be "selected" somehow in the table at first.

[elliottwilliams]

Reopening to wait on the sorting task. The arrivals cannot be sorted in order of arrival time until Timetable is implemented.