Update AGSPoint general category to use properties, and add AGSMutablePoint category for lat/lon. Other misc tidying.
Tidy up notifications code somewhat, and rename a couple of notifications.
Remove static routeDisplayHelperForMapView: helper method from the public eye.
Make things properties when they should be. Also made zoomLevel and centerPoint a read/write property on AGSMapView.

Previously, I hadn't realized you could define properties on a Category and then implement them as such.

In most cases, the implementation didn't change (since an accessor method is named the same as a property getter).
Make AGSMapView basemap a read/write property.

Duh!!!