Version Control With Subversion Source

marker column in "svn status" output. Also minor related changes.

Found by: Fabian Cenedese <Cenedese {_AT_} indel.ch>

* src/en/book/ch09-reference.xml
(svn.ref.svn.c.status): Add a description of the tree conflict field.
Update other column numbers. Update the examples accordingly. Add a
description of the eighth column being blank, to avoid uncertainty.
Fix grammar.