Version Control With Subversion Source

* trunk/src/de/book/ch03-advanced-topics.xml
- Ticket #138 (Externals Definitions), cf.
http://www.svnbook.de/ticket/138.

Tell web crawlers to stop crawling the older versions of the book.
(This was suggested in issue #109.)

* src/en/book/ch05-repository-admin.xml
Minor typo fix, reported by 'drfranket' in issue #108.

* src/en/book/ch02-basic-usage.xml
Typo fix.

Reported by: Jan Keirse <jan.keirse@...>

Fix some typos.

Reported by: Steve Eppley <SEppley@...>

* trunk/src/de/book/ch03-advanced-topics.xml
- Concludes task #137 (cf. http://www.svnbook.de/ticket/137).

* trunk/src/de/book/ch03-advanced-topics.xml
- Ticket #137 (Breaking and Stealing Locks) (cf.
http://www.svnbook.de/ticket/137).

* trunk/src/de/book/ch03-advanced-topics.xml
- Ticket #137 (Discovering Locks), cf.
http://www.svnbook.de/ticket/137.

* trunk/src/de/book/ch03-advanced-topics.xml
- Ticket #137 (Creating Locks) (cf.
http://www.svnbook.de/ticket/137).

* src/en/book/ch02-basic-usage.xml
Fix typo. (Issue #105.)