Reset collision tag on visualiser boat after displaying collision

- Modified View3D to index subjects rather than shapes by source ID
- Enforced one collision per boat on server to reduce rendering load
- Changed collision radius to less than bounce radius
- Fixed game-breaking null command bug

#story[1195]

racevisionGame/src/main/java/mock/model/commandFactory/CollisionCommand.java

@@ -29,17 +29,18 @@ public class CollisionCommand extends ObserverCommand {
     public void execute() {
         this.azimuth = Azimuth.fromDegrees(boat.getBearing().degrees() - 180d);
         this.startingPosition = boat.getPosition();
-        this.distance = 30;
+        this.distance = 60;
         boat.setVelocityDefault(false);
     }
 
     @Override
     public void update(Observable o, Object arg) {
         if(GPSCoordinate.calculateDistanceMeters(boat.getPosition(), startingPosition) < distance) {
-            boat.setPosition(GPSCoordinate.calculateNewPosition(boat.getPosition(), 2, azimuth));
+            boat.setPosition(GPSCoordinate.calculateNewPosition(boat.getPosition(), 3, azimuth));
         } else {
             race.deleteObserver(this);
             boat.setVelocityDefault(true);
+            boat.setColliding(false);
         }
     }
 }