Improved 'load more' logic for infinite-scroll lists. Now load trigger is based on constant proximity to the bottom of content (not the ratio of scrolled distance). Also we check if we need to load more following a successful load, in addition to when we stop scrolling.
Fixed weird behavior with infinite scrolling caused by new logic that loads based on absolute distance from content bottom, not ratio. Needed to make exception for case where contentOffset is negative, specifically when table is animating back after drag-refresh.
Cleaned up infinite-scroll changes. No longer trying to load 'more' again after a load from the table delegate - this causes UI issues.