Version Control With Subversion Source

* en/book/ch09-reference.xml
(svn.ref.svn.c.blame): Demonstrate how to ignore whitespace-only
changes with 'svn blame'.

Fix issue #152 ("Prefer 'svn patch' over 'patch' in book recommendations").

* en/book/ch02-basic-usage.xml,
* en/book/ch04-branching-and-merging.xml
Note 'svn patch' in places where 'patch' is also mentioned, and use
'svn patch' instead of 'patch' in examples.

* en/book/ch04-branching-and-merging.xml
Edits from my read-thru of Chapter 4 (including the removal of the
seemingly unnecessary zone="" attribute found on some <indexterm>
tags...)

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.