Version Control With Subversion Source

earnest to the Subversion book.

* en/book/ch05-repository-admin.xml
Oy. Major reworking here. I've decided to document 'svnrdump'
closer to 'svnadmin dump', as well as to break up the 'svnsync' docs
into a few more subsections.

* en/book/ch09-reference.xml
Add a whole new reference section with (admittedly skeletal)
documentation for svnrdump.