pgsql-server: Various minor improvements to the SGML documentation: fix

Log Message:
-----------
Various minor improvements to the SGML documentation: fix some incorrect
SGML markup, add a "deprecated features" section to the 8.0 release
notes, untabify release.sgml and runtime.sgml, and make some other
minor improvements.

Modified Files:
--------------
pgsql-server/doc/src/sgml:
errcodes.sgml (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/errcodes.sgml.diff?r1=1.7&r2=1.8)
problems.sgml (r2.18 -> r2.19)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/problems.sgml.diff?r1=2.18&r2=2.19)
release.sgml (r1.287 -> r1.288)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/release.sgml.diff?r1=1.287&r2=1.288)
runtime.sgml (r1.278 -> r1.279)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/runtime.sgml.diff?r1=1.278&r2=1.279)
xfunc.sgml (r1.85 -> r1.86)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/xfunc.sgml.diff?r1=1.85&r2=1.86)
pgsql-server/doc/src/sgml/ref:
alter_index.sgml (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/alter_index.sgml.diff?r1=1.3&r2=1.4)
alter_sequence.sgml (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/alter_sequence.sgml.diff?r1=1.7&r2=1.8)
create_table_as.sgml (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/create_table_as.sgml.diff?r1=1.22&r2=1.23)
create_tablespace.sgml (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/create_tablespace.sgml.diff?r1=1.3&r2=1.4)
psql-ref.sgml (r1.120 -> r1.121)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.120&r2=1.121)
release_savepoint.sgml (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/release_savepoint.sgml.diff?r1=1.1&r2=1.2)
rollback_to.sgml (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/rollback_to.sgml.diff?r1=1.2&r2=1.3)
select_into.sgml (r1.29 -> r1.30)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/select_into.sgml.diff?r1=1.29&r2=1.30)