Version Control With Subversion Source

* en/book/styles.css
* en/stylesheets/custom-html-stylesheet.xsl
Add a custom header that warns readers about the in-between-ness of
this (trunk) version of the book.

Create the English 1.7 maintenance branch.

Create 1.7 version placeholder directory.

Edited wiki page SvnBook17Status through web user interface.

Edited wiki page SvnBook17Status through web user interface.

* en/book/ch09-reference.xml
Complete my read-thru of Chapter 9 (Reference), adding an example of
'svnlook tree --full-paths' and documenting the svn:rdump-lock property.

* en/book/ch09-reference.xml
Document the 'mine-conflict' and 'theirs-conflict' arguments to 'svn
resolve --accept'.

* en/book/ch09-reference.xml
Trade an obnoxious full listing of everything that 'svn info' might
print for a more concise listing of information classes. The
examples reveals the details well enough.

* en/book/ch09-reference.xml
Mostly minor markup/wording fixes, but also give an example of 'svn
delete --keep-local'.

Close issue #75 'ch04: svn merge --reintegrate does not match
any of the 3 usage patterns' and issue #134 'ch09: merge
reference should mirror changes made to 'svn merge --help'
text in 1.7'.

* en/book/ch09-reference.xml

(svn.ref.svn.sw): Note --ignore-ancestry's rather important
effect on 'svn merge' beyond what it shares with 'svn diff'.

(svn.ref.svn.c.merge): Rework 'svn merge' reference to more
closely track the revised 'svn merge --help' text for 1.7.