Allow user of scroller library to know if the scroller library was what triggered the draw of the table.

This one is a little hard to explain. Basically we found that we needed to be able to differentiate between redraws of the table because of infinite scrolling and redraws because of other events. This adds a bTriggeredDraw flag on the oScroller object available via fnSettings() so that the user can query what event caused the redraw. We found it useful and thought we'd share.