Version Control With Subversion Source

* appd.xml: new appendix, all about WebDAV/DeltaV and Autoversioning.
Not yet finished, but will be soon. Need to pick jerenkrantz' brain
about the httpd-2.1 generic-locking he created. Will finish this
later tonight.

* ch07.xml (WebDAV): hack this section down quite a bit, move lots of
its information into Appendix D. Create a xref to Appendix D.