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/shared/model/Boat.java

@@ -98,6 +98,11 @@ public class Boat extends Collider {
      */
     private boolean sailsOut = true;
 
+    /**
+     * Indicates whether boat is currently involved in a collision
+     */
+    private boolean isColliding = false;
+
     /**
      * Constructs a boat object with a given sourceID, name, country/team abbreviation, and polars table.
      *
@@ -407,7 +412,7 @@ public class Boat extends Collider {
     @Override
     public boolean rayCast(Boat boat) {
         if(boat != this) {
-            return rayCast(boat, 100);
+            return rayCast(boat, 15);
         } else return false;
     }
 
@@ -419,4 +424,12 @@ public class Boat extends Collider {
             notifyObservers(e);
         }
     }
+
+    public boolean isColliding() {
+        return isColliding;
+    }
+
+    public void setColliding(boolean colliding) {
+        isColliding = colliding;
+    }
 }

racevisionGame/src/main/java/shared/model/Mark.java

@@ -29,11 +29,6 @@ public class Mark extends Collider{
      */
     private GPSCoordinate position;
 
-    /**
-     * Repulsion radius of the mark
-     */
-    private double repulsionRadius = 50;
-
     /**
      * Constructs a mark with a given source ID, name, and position.
      * @param sourceID The source ID of the mark.
@@ -97,7 +92,7 @@ public class Mark extends Collider{
 
     @Override
     public boolean rayCast(Boat boat) {
-        return rayCast(boat, repulsionRadius);
+        return rayCast(boat, 15);
     }
 
     @Override