Simplified feeditemlist_item layout
Add the concept of a FeedItem that is "in progress"

A FeedItem should be considered "in progress" when the user started
listening or watching the media, but did not complete it yet.
Indicate "unread"/"in progress" state of individual feed items
Show number of "in progress" episodes for each feed
Enable transition to "read" and "unread" states for "in progress" items
Use DateFormat.MEDIUM for dates
Extract setting of read/undread state to a FeedItem method
Created constants for feeditem selections
Added methods for getting cursors with different feeditem
column selections
Items that are in progress aren't unread anymore
Implemented FeedManager.Task

FeedManager.Task should be used to do operations in the background and
let callers specify a callback object to be notified when the operation
has completed.
Created method for loading extra information of a feeditem
Implemented Asynchronous description loading in Itemdescriptionfragment
Added cachedDescription and cachedContentEncoded
Removed unused constructor
Renamed methods
Don't change playback completion date

Don't change the playback completion date when marking an episode as
"read" or "unread"
Save media after changing its position
Save media when marking all items as "read"

The unreadItems list contains items that are "in progress", so we need
to save the media.
Added methods for searching descriptions of feeditems in the database.