Version Control With Subversion Source

New [working-copy] section with `exclusive-locking-clients` and `exclusive-locking` runtime configuration variables.
- http://subversion.apache.org/docs/release-notes/1.8.html#exclusivelocking
- http://subversion.tigris.org/issues/show_bug.cgi?id=4176

* en/book/ch07-customizing-svn.xml
Added new [working-copy] section with relevant configurable variables.

`svndumpfilter` in Subversion 1.8 accepts new `--drop-all-empty-revs` option.
- http://svn.apache.org/r1451462
- http://subversion.tigris.org/issues/show_bug.cgi?id=3681

* en/book/ref-svndumpfilter.xml
(svn.ref.svndumpfilter.sw.drop_all_empty_revs):
new option for `svndumpfilter` exclude/include commands.

Document third parameter to post-commit hook (txn-name) introduced in 1.8
- https://subversion.apache.org/docs/release-notes/1.8.html#hooks-post-commit
- https://sourceforge.net/p/svnbook/tickets/217/
Patch by Andreas Stieger.

`svnlook diff` in Subversion 1.8 accepts `--diff-cmd CMD`, `--ignore-properties` and `--properties-only` options.
- http://svn.apache.org/r1407905
- http://svn.apache.org/r1413449
- http://subversion.apache.org/docs/release-notes/1.8.html#svnlook-diff

* en/book/ref-svnlook.xml
New options for `svnlook diff` command:
- (svn.ref.svnlook.sw.diff_cmd): --diff-cmd CMD,
- (svn.ref.svnlook.sw.ignore_properties): --ignore-properties,
- (svn.ref.svnlook.sw.properties_only): --properties-only.

`svn diff` in Subversion 1.8 accepts `--no-diff-added` option.
- http://svn.apache.org/r1433958
- http://subversion.apache.org/docs/release-notes/1.8.html#svn-diff
* en/book/ref-svn.xml
(svn.ref.svn.sw.no_diff_added): New option `--no-diff-added`
for `svn diff`.

`svn diff` in Subversion 1.8 accepts `--properties-only` option.
- http://svn.apache.org/r1336110
- http://subversion.apache.org/docs/release-notes/1.8.html#svn-diff
* en/book/ref-svn.xml
(svn.ref.svn.sw.properties_only): New option `--properties-only`
for `svn diff`.

`svn diff` in Subversion 1.8 accepts `--patch-compatible` option.
- http://svn.apache.org/r1239553 & http://svn.apache.org/r1239561
- http://subversion.apache.org/docs/release-notes/1.8.html#svn-diff
* en/book/ref-svn.xml
(svn.ref.svn.sw.patch_compatible): New option `--patch-compatible`
for `svn diff`.

`svn diff` in Subversion 1.8 accepts `--ignore-properties` option.
- http://svn.apache.org/r1239553
- http://subversion.apache.org/docs/release-notes/1.8.html#svn-diff
* en/book/ref-svn.xml
(svn.ref.svn.sw.ignore_properties): New option `--ignore-properties`
for `svn diff`.

Follow-up to https://sourceforge.net/p/svnbook/source/5006/

Updated the description of the mod_dav_svn keyword expansion feature
with a paragraph taken from the patch by Andreas Stieger:
https://sourceforge.net/p/svnbook/tickets/193/

Minor fix (removed extra newline).