Moved generic ray casting to Collider abstract class

- Boat is now collider
- Collider subclasses specify their own collision ray and collision handler

#story[1100]

racevisionGame/src/test/java/mock/model/MockBoatTest.java

@@ -3,7 +3,6 @@ package mock.model;
 import org.junit.Before;
 import org.junit.Test;
 import shared.model.Bearing;
-import shared.model.CompoundMark;
 import shared.model.GPSCoordinate;
 import shared.model.Mark;