grim/purple-objects-docbook

cleaned up some output and made the targets that depend on specific sheets depend on the specific sheet
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<chapter id="hashes">
<title>Hashes</title>
<figure id="hashes-hierarchy">
<title>Hash Object Hierarchy</title>
<graphic fileref="graphs/hashes.png"/>
</figure>
</chapter>