Code review for standard_conforming_strings patch. Fix it so it does not

Code review for standard_conforming_strings patch.  Fix it so it does not
throw warnings for 100%-SQL-standard constructs, clean up some minor
infelicities, try to un-break ecpg to the best of my ability.  (It's not clear
how ecpg is going to find out the setting of standard_conforming_strings,
though.)  I think pg_dump still needs work, too.