code: public Collision getCollision(String name)
      {
          if (collisions.containsKey(name))
          {
              return collisions.get(name);
          }
          throw new LionEngineException(ERROR_COLLISION_NOT_FOUND + name);
      }
docs: Get a collision data from its name.
  
  @param name The collision name.
  @return The collision reference.
  @throws LionEngineException If the collision with the specified name was not found.