title: Adding an overlay to the camera view rather than the map view
body: <p>I am trying to add a 'target' which would be represented as a circle which must always remain at the center of the current map view. Looking through the API I see a lot about adding Markers, Shapes, Ground overlays and Tile overlays but none seem to be adaptable to my needs.</p>
  
  <p>Basically they are all used to draw elements 'on the map' at specified locations. What I need is some sort of overlay for the actual camera view. A good example would be when looking through the lens of the camera where a circle denotes the center of the frame.</p>