'Delete feed' feature added, other minor improvements

• A new 'Delete feed' feature has been added. To delete an unwanted feed, log in to your account, open 'My Feeds' page, click on 'Expand details' for the feed you want to delete and see the 'Delete feed' link in the feed's details. Note that you can later undelete previously deleted feeds via 'Add feeds to your account / Undelete feeds' feature on the same 'My Feeds' page.
• Sometimes the login procedure would not work properly (you would see full feeds' details in 'My Feeds' page though at the top of the same page you would see a 'not logged in' message) -- fixed.
• Context help and FAQ has been updated.