Version Control With Subversion Source

* src/en/book/ch09-reference.xml
Tag tweaks only.

* src/en/book/ch09-reference.xml
Expand reference section titles with short descriptions of each tool.

Try to reduce the verbosity of the reference chapter, eliminating
information of questionable continued value and presenting other
information in a more concise fashion.

* src/en/book/ch09-reference.xml
Lose 'Changes' and 'Accesses repository' bits from reference
entries, and trade 'Alternate names' for additional <refname>s.

Update some web/email references.

Mark a completed task.

* src/en/book/ch04-branching-and-merging.xml
Complete my read-thru edits/updates for this chapter.

* src/en/book/ch04-branching-and-merging.xml
Formatting, comment, and "trailing prompt" changes only.

Edited wiki page SvnBook16Status through web user interface.

* src/en/book/ch06-server-configuration.xml
Complete my read-thru edits for this chapter.

No longer represent high-level logging as Apache-only.

* src/en/book/ch09-reference.xml
(svn.ref.svnserve.sw): Point folks to new high-level logging
section.
(svn.ref.mod_dav_svn.conf.logging): Move high-level logging details
from here...

* src/en/book/ch06-server-configuration.xml
(svn.serverconfig.operational-logging): ... to here.
(svn.serverconfig.httpd.extra.logging): Update xref per the
aforementioned relocation of logging details.