Completely overhaul Gliederung.md

Based on (in fact, to be honest, mostly copied from) the
Kurzpräsentation slides.
More info about pressure in centrifuges
Better info about WinCC

Langner couldn’t find any evidence of WinCC use in Natanz, so perhaps
that synchronization didn’t actually happen.
Add slide about SCADA, controllers
Add sections and subsections

They show up in a small info bar at the bottom of each slide.

This also adds a commented-out ToC slide, but I don’t think we want to
have that.
Add slide about propagation