Version Control With Subversion Source

Fix issue #114 'Consider re-adding pre-merge-tracking
examples'.

* en/book/ch04-branching-and-merging.xml
(svn.branchemerge.basicmerging.stayinsync): Add a new
sidebar 'Keeping a Branch in Sync Without Merge Tracking'.

Wrap-up my chapter 4 final read through review.

* en/book/ch04-branching-and-merging.xml
(svn.advanced.vendorbr,
svn.advanced.vendorbr.svn_load_dirs): Some minor wording tweaks.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.tags.mkcomplex): Account for the current state
of the art in 'svn diff' and 'svn patch'.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.switchwc): Don't imply we are using a
single ongoing example in this chapter. Add a tip re
the need to use --ignore-ancestry for some switches.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.advanced.finalword): Some run-of-the-mill
rewording and a refresh of the best practices list.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.advanced.pre1.5clients): Some minor wording
changes and a link to the 'merge tracking' sidebar.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.advanced.ancestry): Index the term 'ancestry'.
Add a tip about --ignore-ancestry's effect on merge tracking.

* en/book/ch04-branching-and-merging.xml
(svn.branchmerge.advanced.logblame): Minor wording tweaks and
correct the sampel 'svn log -q output', it should not show
line count.

* 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
Try another approach to fixing links to Reference sections, adding
the text 'in <xref linkend="svn.ref"/>' after each such reference in
the book that points to an ambiguously named piece of the Reference.

* en/book/ch04-branching-and-merging.xml

(svn.branchmerge.nomergedata.impicit.mergeinfo): New id
attribute for the 'Natural History and Implicit Mergeinfo'
sidebar.

(svn.branchmerge.advanced.reintegratetwice): A few minor
wording changes and a link to the 'Natural History and
Implicit Mergeinfo' sidebar when we use the former term.