A lot of work on the presentation

The shell auto-image now runs code and turns the output into an image
that is embedded into the document

The prompt is configurable in /bin/prompt

The first draft is done up until the references section

shell/first-diff

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+cd /tmp/demo
+sed -i 's/Hello/Hello World/' ./greeting.py
+echo '$ git diff'
+git -c color.ui=always diff