DirectionsRequest "optimizeWaypoints" always true

[MauriFont]

In DirectionsRequest the method setOpt() is useless since the string is generated when the object is created thus calling setOpt(false) does nothing and "optimizeWaypoints" will always be true since is the default value.

Solution would be to overload the constructor, even more. I don't pull a request because It would bother some users or there would be too much constructors.