Book fixes.
Book fixes.

Patch by: Jennifer Bevan <jen@bounce.alouysius.net>
          Mason Thomas <mlt_svn@sbcglobal.net>
(Partly patches, partly feedback.)

* doc/book/book/ch05.xml: Fix several typos, add a few omitted words,
  fix a few &mdash; spacing problems.  Convert many uses of the word
  "which" into "that", where appropriate.  General grammar fixes.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion