Fix up references to "PostgreSQL" rather than "Postgres". Was roughly
 evenly split between the two before. ref/ files not yet done.

the interactive docs.

flexible about the extension of the graphic files, allow for other formats
in print output.  (Generating these formats is not implemented yet.)

to the thing you get from running initdb.  That's called a database cluster
(per SQL).

names for the HTML files (e.g., not x4856.htm).

A few other changes, but I forget what :(

 of Norm's Modular Style Sheets and jade/docbook.
From Vince Vielhaber <vev@michvhf.com>.

Fix Id tag in chapter headings to allow meaningful file names in html.