Finished implementing unit tests for the User model, that test the automatic upkeep of the cached unread entries count for each folder.
The views now use the cached unread entries count for each feed, instead of executing an SQL count on every page load.

The only exception is the "all" folder, which is still counting records. I still have to implement caching in the DB the total numer of unread entries in all the feeds subscribed by a given user.