Version Control With Subversion Source

* en/book/ch06-server-configuration.xml
Point to the canonical homepage for ViewVC.

Reported by: gstein

* en/book/ch06-server-configuration.xml
Fix a spelling oops and some ambiguously phrased prose.

Reported by: d.s{__AT__}daniel.shahaf.name

Finish Issue 3 ("Add documentation for running svnserve under
xinetd").

* en/book/ch06-server-configuration.xml
(svn.serverconfig.svnserve.invoking.xinetd): New section.

Content by: Zdenek Wagner <zdenek.wagner{__AT__}gmail.com>
(Tweaked by me.)

Fix issue84 ("fr-current Title missing").

* 1.5/fr/book/ch04-branching-and-merging.xml
Add missing section divider/title.

Reported by: oXidFoX

* en/book/ch02-basic-usage.xml
(svn.tour.importing.naming): Warning about how different OSes
allow/disallow certain path names, and recommend that users put some
thought into such things.

* 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.