News auto-archival and cleanup

News posts now auto-archive after a year to avoid overwhelming new players
with 20+ years of history.

Archived entries are not listed at login nor in 'news', but they can be
seen with 'news all', and they can be displayed with 'news next' after
all other non-archived messages have been read.

Credit goes to Zathras for the initial idea and for identifying dozens
of less newsworthy entries, which were removed to unclutter the board.