* Change terminology to refer to "seen" articles as "deleted".

* Change terminology to refer to "seen" articles as "deleted".

* Introduce new marking, "browsed", to indicate articles whose headers
  have been shown in a news-group buffer.  These "browsed" markings
  are used to prevent a common problem with cross posts: after having
  marked an article in one group, re-marking the cross-posted article
  differently in another group clobbers the original markings.  The
  news reader now examines the "browsed" marking, and does not re-mark
  any cross post that has already been "browsed".

* Change code that selects initial header when opening a news-group
  buffer for the first time.  New code does not automatically expand a
  thread whose first message is "deleted".