pgsql: Split contrib documentation into extensions and programs

Split contrib documentation into extensions and programs

Create separate appendixes for contrib extensions and other server
plugins on the one hand, and utility programs on the other.  Recast
the documentation of the latter as refentries, so that man pages are
generated.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/1c882e07da553d792f479beb92b4729a4c0bd8de

Modified Files
--------------
doc/src/sgml/contrib.sgml          |   89 ++++++++++++++++++---
doc/src/sgml/docguide.sgml         |    9 ++
doc/src/sgml/oid2name.sgml         |   64 +++++++++------
doc/src/sgml/pgarchivecleanup.sgml |  106 +++++++++++++-----------
doc/src/sgml/pgbench.sgml          |  155 ++++++++++++++++++++---------------
doc/src/sgml/pgstandby.sgml        |  135 ++++++++++++++++---------------
doc/src/sgml/pgtestfsync.sgml      |   47 ++++++++---
doc/src/sgml/pgtesttiming.sgml     |   68 +++++++++++-----
doc/src/sgml/pgupgrade.sgml        |  157 ++++++++++++++++++++++--------------
doc/src/sgml/stylesheet-man.xsl    |   10 +++
doc/src/sgml/vacuumlo.sgml         |  118 +++++++++++++++------------
11 files changed, 597 insertions(+), 361 deletions(-)