Version Control With Subversion Source

More book work.

* doc/book/book/ch00.xml: rewrite the overview of the book's chapters,
based on feedback from Ben Gross.

* doc/book/TODO: mark this task finished.

* doc/book/book/ch06.xml: add some notes.

* doc/book/book/ch06.xml: create chapter outline, ready to fill in.

Get chapter 6 started.

* doc/book/TODO: readjust my notes & outline.

* doc/book/book/ch06.xml: start the section with an enhanced feature
comparison of the two network servers.

Add (new) empty chapter 6, and make the book compile again.

* book.xml: add ch09.xml to compile list

* ch06.xml: new file.

* ch00.xml, ch01.xml, ch03.xml, ch04.xml, ch05.xml, ch07.xml,
ch08.xml, ch09.xml, appa.xml, appe.xml, appf.xml: update all
references to 'svn-ch-[678]', and replace with 'svn-ch-[789]'
accordingly.

Rename book chapters 6, 7, 8 to 7, 8, 9. Third commit.

Rename book chapters 6, 7, 8 to 7, 8, 9. Second commit.

Rename book chapters 6, 7, 8 to 7, 8, 9. First commit.

(In case you're wondering why I'm doing these renames in three
separate commits, it's issue #1516. Very annoying:

$ svn mv ch08.xml ch09.xml
A ch09.xml
D ch08.xml

$ svn mv ch07.xml ch08.xml
subversion/libsvn_wc/copy.c:156: (apr_err=150002)
svn: 'ch08.xml' is scheduled for deletion; it must be committed
before being overwritten
)

* doc/book/TODO: a bunch of book work to be done RSN.

Fix some typos in the book's sample code. This patch provided by Tez
Kamihira <tez@...>. Thanks, Tez!

* doc/book/TODO: add book task for cmpilato.