Version Control With Subversion Source

Clarifications based on suggestions from Robert P. J. Day
<rpjday@...>.

* src/en/book/ch01.xml

(Installing Subversion): explain APR, clarify that apache is not required.

(A Quick Start): clarify that 'project' is just a directory. note
that the branchs/tags/trunk structure is merely a
convention, not a requirement.

* src/en/book/ch02.xml

(Working Copies): mention that you can have multiple working copies.