Mention libpq env. and pgpass in psql manual page

I have committed to CVS HEAD and 8.0.X:

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Mention that some psql environment variables come from libpq and note
more variables can be found in the libpq manual section.

Mention .pgpass in the psql manual page section dealing with connection
parameters and point to the libpq section for more details.

Backpatch to 8.0.X.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: doc/src/sgml/ref/psql-ref.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/ref/psql-ref.sgml,v
retrieving revision 1.132
diff -c -c -r1.132 psql-ref.sgml
*** doc/src/sgml/ref/psql-ref.sgml	22 Jan 2005 23:22:19 -0000	1.132
--- doc/src/sgml/ref/psql-ref.sgml	11 Feb 2005 04:14:48 -0000
***************
*** 348,354 ****
        
        
        
!       Makes psql prompt for the user name and
        password before connecting to the database.
        
  
--- 348,354 ----
        
        
        
!       Forces psql to prompt for the user name and
        password before connecting to the database.
        
  
***************
*** 406,426 ****
        
        
        
!       Cause psql to prompt for a
!       password before connecting to a database. This will remain set for
!       the entire session, even if you change the database connection
!       with the meta-command \connect.
        
  
        
!       In the current version, psql
!       automatically issues a password prompt whenever the server
!       requests password authentication. Because this is currently based
!       on a hack, the automatic recognition might mysteriously fail,
!       hence this option to force a prompt. If no password prompt is
!       issued and the server requires password authentication, the
!       connection attempt will fail.
        
        
      
  
--- 406,430 ----
        
        
        
!       Forces psql to prompt for a
!       password before connecting to a database.  
        
  
        
!       psql should automatically prompt for a
!       password whenever the server requests password authentication.
!       However, currently password request detection is not totally
!       reliable, hence this option to force a prompt. If no password
!       prompt is issued and the server requires password authentication,
!       the connection attempt will fail.
        
+ 
+       
+       This option will remain set for the entire session, even if you
+       change the database connection with the meta-command
+       \connect.
+       
+ 
        
      
  
***************
*** 508,514 ****
      some typing by setting the environment variables
      PGDATABASE, PGHOST,
      PGPORT and/or PGUSER to appropriate
!     values.
      
  
      
--- 512,521 ----
      some typing by setting the environment variables
      PGDATABASE, PGHOST,
      PGPORT and/or PGUSER to appropriate
!     values. (For additional environment variables, see .) It is also convenient to have a
!     ~/.pgpass</> file to avoid regularly having to type in
!     passwords. See  for more information.
      
  
      
***************
*** 2460,2466 ****
  
      
       
!       Default database to connect to
       
      
     
--- 2467,2473 ----
  
      
       
!       Default connection database