PostRank version of OATP feed

This new version of the OATP feed shows levels of user engagement, as this concept is defined by PostRank. You may either view all the posts in the feed with their engagement levels showing, or filter the feed and view only the posts at certain levels of engagement. This is an experiment. User engagement as measured by PostRank may not help identify the most important OA developments in the OATP feed. But if it does, it's one way to filter the high-volume OATP feed without skimming or excluding entire subtopics.