Version Control With Subversion Source

* en/book/ch07-customizing-svn.xml
Swap the 'Config' and 'Servers' sections, and give them more
descriptive names.

* en/book/ch02-basic-usage.xml,
* en/book/ch03-advanced-topics.xml,
* en/book/ch04-branching-and-merging.xml,
* en/book/ch05-repository-admin.xml,
* en/book/ch06-server-configuration.xml
Update some links to reference material to be more precise.

* en/book/styles.css
Style tweaks.

* tools/base-html-stylesheet.xsl
Disable a bunch of TOCs. This makes the single-page HTML not have a
bunch of inline TOCs.

* tools/chunk-stylesheet.xsl
Try to re-enable certain TOCs here for chunked HTML output that were
disabled in base-html-stylesheet.xsl. This ... uh ... doesn't seem
to work, though.

Split the book into parks, and further split the ginormous Chapter 9
Reference into a bunch of smaller focused references.

* en/book/book.xml
Add character entities for the new reference sections, and break the
book up into distinct <part>s.

* en/book/styles.css
Stylistic tweaks for TOCs.

* en/book/ch09-reference.xml
Delete this, but divide its contents up into ...

* en/book/ref-davmodules.xml,
* en/book/ref-props.xml,
* en/book/ref-reposhooks.xml,
* en/book/ref-svn.xml,
* en/book/ref-svnadmin.xml,
* en/book/ref-svndumpfilter.xml,
* en/book/ref-svnlook.xml,
* en/book/ref-svnmucc.xml,
* en/book/ref-svnrdump.xml,
* en/book/ref-svnserve.xml,
* en/book/ref-svnsync.xml,
* en/book/ref-svnversion.xml
... all of these smaller, more focused <reference> files.

* en/book/ch06-server-configuration.xml
Remove markup from section <title>.

* en/book/ch04-branching-and-merging.xml
* en/book/ch09-reference.xml
Rename some busted section id's (s/branchemerge/branchmerge/).

Merge from ^/trunk/en r4392 (followup to r4387) and r4393 (new
'To Branch or Not to Branch?' section).

Finish isse 173 ("ch04: Consider noting when *not* to use branches").

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.when): New section cover the pros and cons of
branching.

* en/book/ch00-preface.xml
(svn.intro.righttool): Rework the "comparison" paragraph to point
out why the DVCS tools do well what they do well, and try to note
that centralized systems allow mixed-rev working copies without
using the terms "mixed-rev" or "working copies" (which aren't yet
introduced). Sheesh.

Suggested by: danielsh

Merge from ^/trunk/en r4390 (DAV proxy instructions disclaimer).