Version Control With Subversion Source

* ch06-server-configuration.html: sketch outline of write-thru-proxy docs.

Document new options in svn 1.5:

--accept
--changelist
--depth
--keep-changelist
--keep-local
--record-only
--remove
--use-merge-history
--with-all-revprops
--with-revprop

And I found two bugs!

Fixes issue #84.

* src/en/book/ch09-reference.xml (svn.ref.svn.sw): Frozzle the cons!

Fix some typos and add a sidebar about SVNKit.

Document sparse directories.

Fixes issue #89.

* src/en/book/ch03-advanced-topics.xml (svn.advanced.sparsedirs):
Document and provide a few examples.

Add initial documentation for the changelists feature. This is a
reworking of a blog post I wrote for CollabNet's Subversion blog,

http://blogs.open.collab.net/svn/2007/07/one-quality-of-.html

reproduced here as part of the book with the permission of Guido
Haarmans, the CollabNet Marketing dude for whom the original blog post
was composed.

* ch05-repository-admin.xml: fix wording.

* ch06-server-configuration.html: point to list of ch09 mod_dav_svn directives.

* appc-webdav.xml: update webdav interop docs for both XP and Vista.

Update code samples to new 1.5-isms.

Finish Trac ticket #82 by adding a bit about fsfs-reshard.py.