Externalized blacklist

Created blacklist.js, moved blacklist selectors array into blacklist.js,
updated calamine to check for presence of the external array
Refactored how entries are marked as read

Deprecated lucu.feed.markAsRead. Moved around some code. Use openCursor
and cursor.update instead of get-then-put. Fixed a long-standing bug
where sometimes an article was not marked as read, leading to a wrong
number of unread articles displayed in badge after reading last-loaded
article.