LP#1410369: patron message center page in TPac

LP#1410369: patron message center page in TPac

This patch adds My Account tab in TPac for
displaying and managing patron messages.  In particular,
a logged in patron will be able to:

- see a list of their (undeleted) messages
- open a particular message and see it's body;
  doing this automatically marks the message as
  read
- delete messages from either the list or
  single-message views
- mark messages as unread from the list or
  single-message views
- mark messages as read from the list view

Signed-off-by: Galen Charlton <gmc@esilibrary.com>