Freakin' finally...

Started implementing the map view.

Every slippy map implementation (well, Google and Leaflet, anyway) seems
to have a built-in limitation where if it's ever either removed from the
DOM or made invisible, it forgets what size it was, and thus doesn't
center properly.

This posed a problem when presenting the mapView modally.  It took me
all day to figure this out, but I've remedied it by forcing Google Maps
to redraw itself, and recenter on the desired location once the modal
presentation routine finishes.