LastY variable was added to settings

Hello!
I suggest to add variable lastY to settings object. I think it will be good, if developer will have ability to set this value via settings. It can be useful for pages  viewed on mobile devices. I think that default value (=40) is too small for some applications. When I added hook.js to my mobile application, I thought that it didn't work first time, because when I scrolled the page, my finger clicked on the middle of the screen and nothing happened (because lastY was more than 40)), so I guess that placing lastY to settings could do this library more flexible.