info: Improve .NA and first paragraph of change log pages

info: Improve .NA and first paragraph of change log pages

The .NA show up in "info Server", like this:

   Chainsaw !   Changes from KSU Empire to Chainsaw code
    Empire2 !   Changes from the Chainsaw server to the Empire2 Server
    Empire3     Changes from the Empire2 server to the Empire3 Server
    Empire4 !   Changes from the Empire3 server to the Empire4 Server
[...]
       Merc     Changes from KSU code to Merc code
 Old-empire !   Differences from 1.2 to UCB Empire

Tweak them to look like this:

   Chainsaw !   Changes from KSU Empire to Chainsaw (1992-93)
    Empire2 !   Changes from Chainsaw to Empire 2 (1995)
    Empire3     Changes in Empire 3 (1995-96)
    Empire4 !   Changes in Empire 4 (1996-present)
[...]
       Merc     Changes from KSU code to Merc code (1992)
 Old-empire !   Differences from 1.2 to UCB Empire

The first paragraph of Empire2.t refers to "the new Empire 2" server.
Drop "new", because it clearly ain't anymore.  Same for Empire3.t.

The first paragraph of Empire4.t claims "several changes/fixes" have
been made.  Umm, that's only tenuously connected to reality by now.
Rewrite the paragraph.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>