Geodesic: Only show a picture on screen if asked
Geodesic: In fact we are not using Info.done
Geodesic: Saner default values, and a progress bar
Geodesic: Also store the distance field locally
Geodesic: Use infinities, it is nicer
Geodesic: Store everything in Info, get rid of Field
Geodesic: trace geodesics in a customizable color, red by default