Quickbook: Set version for release.

svn path=/trunk/tools/quickbook/; revision=78727
Quickbook: Fix documentation.

Was using a feature I haven't implemented yet.

svn path=/trunk/tools/quickbook/; revision=78728
Quickbook: Backdated changelog for 1.5.8.

Oops, I completely forgot to write this up at the time.

svn path=/trunk/tools/quickbook/; revision=82573
Quickbook: Describe new 1.6 tags.

svn path=/trunk/tools/quickbook/; revision=82589