Version Control With Subversion Source

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.advanced.finalword): Fix an external link.
Temporary fix for issue #172.

Finish issue 30 ("Use common URI in DocBook system identifier"). In
doing so, bump the claimed DocBook version to 4.5.

* en/README
Note that the book is written in DocBook 4.5 now.

* en/book/book.xml
Point to the DocBook 4.5 DTD.

* tools/Makefile.base-po
Remove pre-processing of source files to refer to DocBook 4.5 -- the
source already so refers.

* tools/dtd
Remove these local copies of the Docbook DTDs.

Finish issue 58 ("plain password authentication with Apache").

* en/book/ch06-server-configuration.xml
(svn.serverconfig.httpd.authn.basic, svn.serverconfig.httpd.authn.digest):
Point out which Apache modules are required for Basic and Digest
authentication, as well as the way to select the file-based authn
provider for those types.

* en/book/ch06-server-configuration.xml
(svn.serverconfig.httpd.extra.logging): Document trick for
selectively logging requests (wrapped in typical cmpilato
verbosity, of course).

Finish issue 148 ("ch06: Give suggestions for tuning Apache to
maximize value of ra_serf").

* en/book/ch06-server-configuration.xml
(svn.serverconfig.httpd.perf): New section.

In some of my recent examples, replace
'http://localhost/svn/repositories/repos' with
'http://svn.example.com/repos' for consistency with
the rest of the book.

* en/book/ch03-advanced-topics.xml
* en/book/ch09-reference.xml

Add --show-inherited-props to applicable reference sections.

* en/book/ch09-reference.xml

(svn.ref.svn.sw.show_inherited_props): New option.

(svn.ref.svn.c.propget,
svn.ref.svn.c.proplist): Add content re new option.

* en/book/images/cc-by.png
New image (intended for inclusion with r4200, but ... oops.)

Merge from ^/trunk/en r4328 (dropping mentions of the old -deps
tarball).

* en/book/appa-quickstart.xml
Drop stuff about the -deps tarball. It isn't offered any more, and
INSTALL is the canonical source of installation information anyway.