Fix #1

Setting currentGroup=group when consolidating the currently selected
group (ie, when pulling down the groups list) so the unread count is
accurate.
Fix #2

On-demand item loading, with a "More Items" button. Much, much faster
now. And will stop getting slower as your feeds get more full, which was
becoming a problem and was only going to get worse.
Fix #7

Mark items as read one at a time, but only make the call if it's unread.
Also mark all items in the group is a single call that covers the whole
group, which will be faster and work without loading all the items
first.