implementation limits, do not issue an ERROR; instead issue a NOTICE and use
the max supported value.  Per pgsql-general discussion of 28-Apr, this is
needed to allow easy porting from pre-7.3 releases where the limits were
higher.

Unrelated change in same area: accept GLOBAL TEMP/TEMPORARY as a synonym
for TEMPORARY, as per pgsql-hackers discussion of 15-Apr.  We previously
rejected it, but that was based on a misreading of the spec --- SQL92's
GLOBAL temp tables are really closer to what we have than their LOCAL ones.