Just committed some changes...

I've committed some changes which implement a few new things.

From the CVS log:

Implement nested block comments in the backend and in psql.
Include updates for the comment.sql regression test.
Implement SET SESSION CHARACTERISTICS and SET DefaultXactIsoLevel.
Implement SET SESSION CHARACTERISTICS TRANSACTION COMMIT
and SET AutoCommit in the parser only.
Need to add code to actually do something.
Implement WITHOUT TIME ZONE type qualifier.
Define SCHEMA keyword, along with stubbed-out grammar.
Implement "[IN|INOUT|OUT] [varname] type" function arguments
in parser only; INOUT and OUT throws an elog(ERROR).
Add PATH as a type-specific token, since PATH is in SQL99
to support schema resource search and resolution.

Since some of these changes involve tokens in the parser, you may need
to do a "make clean all install" to get everything sync'd. afaict this
is because we propagate a few of the gram.y token values deeper into the
backend...

- Thomas