psql tab completion

Clean up psql:

Add simple ALTER DATABASE, ALTER TRIGGER, CHECK POINT, CREATE
CONVERSION, CREATE DOMAIN, CREATE LANGUAGE, DEALLOCATE, DROP CONVERSION,
DROP DOMAIN, DROP LANGUAGE, EXECUTE, PREPARE

Complete CAST in CREATE CAST and DROP CAST but doesn't suggest what
should follow.

Add many more SET / SHOW variables to the list.  Taken from SHOW ALL
output.

Complete a case sensitive search to allow \dD, \dd, \dS, \ds, \h, \H to
complete properly.  But there are no matches, then try a case
insensitive search to allow case conversion.  Add all missing help
options.

\Q<tab>    -> \q
\dD<tab>   -> \dD
\dd<tab>   -> \dd
\D<tab><tab><tab> -> \d (with listing of \d? commands)
sel<tab>   -> SELECT


> On the other hand, in psql , tab-completion doesn't seem to
> work for certain commands :
>
>    ALTER DATABASE ; ALTER TRIGGER ; CHECKPOINT ; CREATE CAST ;
>    CREATE CONSTRAINT TRIGGER ; CREATE CONVERSION ; CREATE DOMAIN ;
>    CREATE LANGUAGE ; DEALLOCATE ; DROP CAST ; DROP CONVERSION ;
>    DROP DOMAIN ; DROP LANGUAGE ; EXECUTE ; PREPARE
>
> ( this could be considered a low priority todo item , though )

--
  Rod Taylor