* Cleans up & documents more APIs, especially in location.
* Moves `coordinate` internal and makes use of `location` to retrieve it.
* Moves `title` & `subtitle` internal since part of `MGLAnnotation` protocol.
* Enables `isUpdating` by privately associating weakly with a map view.
As a best practice for the beta and a workaround for #1014.
Also reversed the argument order of the existing init method. Reads better this way, but you’ll likely have to change your initialization to match the new signatures.
