We don't get UITouches from the ArcGIS SDK so just change the delegate methods to handle a CGPoint (we aren't using the UITouch object anyway...). Look into piggy-backing onto the responder chain from MGSMapView later if we really need to.

Signed-off-by: Blake Skinner <bskinner@mit.edu>
Add a delegate method to forward taps.

Signed-off-by: Blake Skinner <bskinner@mit.edu>
Add several methods for subclasses to detect when they have been added/removed from a map view.

Signed-off-by: Blake Skinner <bskinner@mit.edu>
Allow public access to the MGSLayerManagers. This should be used for more advanced layers (for example, MGSLayer backed by an ArcGIS feature layer)

Signed-off-by: Blake Skinner <bskinner@mit.edu>
Add a comment to clarify the spatialReference property's behavior

Signed-off-by: Blake Skinner <bskinner@mit.edu>