Add pg_description table for info on tables, columns, operators, types, and aggregates.  Modify psql with new \dd operator to access description

Rename PG_DATESTYLE to PGDATESTYLE environment variable.
Move environment variable code to a different place so it now works!
Note that regression tests can now run with "setenv PGTZ PST8PDT"
 at the frontend rather than requiring the backend to have TZ set.

Try to save pre-existing TZ environment variable if possible.
Includes code from Keith Parks.

Clean up FloatExceptionHandler elog message source code.

available.
Remove lots of #ifdef'd debugging print statements.

Remove unused old code.

Add: Stratus computer (a fault tolerant Unix box running an Intel I960
processor).

My analysis of the formerly mentioned IPC reinitialization problem was
hampered by an imprecise error message.  I have rewritten it so it is
clearer and more accurate.

The attached patch makes elog() write the message to stderr if there is
no frontend to talk to.

Pointed out by: Pieter Huyser <pieter@inetsys.alt.za>

 for use by recently created macros.

Implement SET keyword = DEFAULT and SET TIME ZONE DEFAULT.
Re-enable JOIN= option in CREATE OPERATOR statement (damaged for v6.2).
Allow more SQL and/or Postgres reserved words as column identifiers
 or, if there are shift/reduce problems, at least as column labels.

Enable SET TIME ZONE using TZ environment variable.

Add istrue() and isfalse() routines to implement SQL3 IS TRUE and IS FALSE.

 This allows mixed-case identifiers if surrounded by double quotes.
Add mention of "with location" clause for "create database" in help.