functions to the core XML code. Per discussion, the former depends on
XMLOPTION while the others do not. These supersede a version previously
offered by contrib/xml2.
Mike Fowler, reviewed by Pavel Stehule
remove transactions
use create or replace function
make formatting consistent
set search patch on first line
Add documentation on modifying *.sql to set the search patch, and
mention that major upgrades should still run the installation scripts.
Some of these issues were spotted by Tom today.
alias with the old name for backwards compatibility. Per discussion,
the old name is actively wrong because validity and well-formedness
have different meanings in XML.
