Add hasNext()

[Mithrandir21]

• Added hasNext() function to ChainTourGuide.
• Added info to Readme about disableClickThroughHole(...).

The logic for hasNext() already exists in the next(), but by making it publicly accessable users of the ChainTourGuide can use hasNext() to determine if the end of the chain has been reached. This will allow performing some kind of action at the end of a chain of actions, like tour completed, don't run again settings.