calculation for number of rows to be drawn was wrong, fixed now. To
compensate for overshooting with fast scrolling, speed is calculated
using previous scrollY in rows/scroll, and used to render more rows.
Also, the "scrollend" event is used to load more at the end of a scroll
always. Since this isn't available on safari/webkit(2gtk), a polyfill
has been added.
Harvey Tindall
47188da5c2