added TODO's after practice talk
collected diagrams in one ODG file
made arrows white - no success exporting the modified drawings to PNG yet
tidied up some bits, mainly introduced linebreaks into code examples to prevent scrollbars
collected design goals in one slide
cleaned up the end part of the presentation
got images exported properly via Inkscape
more polishing
more polishing, distinguish now between "show" slides with very little text and "tell" slides which unabashedly have lots of text
final version?