* Fix help text ordering

* Add back --set-session-authorization to pg_dumpall.  Updated the docs
for that.  Updated help for that.

* Dump ALTER USER commands for the cluster owner ("pgsql").  These are
dumped AFTER the create user and create database commands in case the
permissions to do these have been revoked.

* Dump ALTER OWNER for public schema (because it's possible to change
it).  This was done by adding TOC entries for the public schema, and
filtering them out at archiver time.  I also save the owner in the TOC
entry just for the public schema.

* Suppress dumping single quotes around schema_path and DateStyle
options when they are set using ALTER USER or ALTER DATABASE.  Added a
comment to the steps in guc.c to remind people to update that list.

* Fix dumping in --clean mode against a pre-7.3 server.  It just sets
all drop statements to assume the public schema, allowing it to restore
without error.

* Cleaned up text output.  eg. Don't output -- Tablespaces comment if
there are none.  Same for groups and users.

* Make the commands to DELETE FROM pg_shadow and DELETE FROM pg_group
only be output when -c mode is enabled.  I'm not sure why that hasn't
been done before?!?!

This should be good for application asap, after which I will start on
regression dumping 7.0-7.4 databases.

Christopher Kings-Lynne