code: public CollisionFormula getCollisionFormula(String name)
      {
          if (formulas.containsKey(name))
          {
              return formulas.get(name);
          }
          throw new LionEngineException(ERROR_FORMULA + name);
      }
docs: Get the collision formula from its name.
  
  @param name The collision formula name.
  @return The collision formula from name reference.
  @throws LionEngineException If formula not found.