Version Control With Subversion Source

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

(svn.branchmerge.basicmerging.reintegrate): Put an ellipse in the
example where we delete a branch. We only say you can delete,
you don't need to in 1.8 to reuse it and we are not doing so in
our ongoing ch 4 example.

(svn.branchmerge.basicmerging.mergeinfo): Rework examples to use
the forthcoming ch 4 sample repository, adjust prose to reflect
1.8 behavior, and make a few wording tweaks.

(svn.branchmerge.basicmerging.mergeinfo.operativerevs): New sidebar.