LazyLoad for horizontal scrolling

[thomasd]

I needed the lazy loading for horizontal scrolling containers and changed your class a little bit. Now the LazyLoad-Class has the option "mode" which can be either "vertical" or "horizontal" (default is "vertical"). In "vertical"-mode the class checks the y-value of the scrolling (same behaviour as before) in "horizontal"-mode the class checks the x-value. Everything else stays the same.

The code: http://gist.github.com/255921