Add some text to test the script feature

This is far from complete, but I have to focus on the slides first.
Add slides for second lecture
Add slide about IEEE 754
Set body class scylec-mode-script

Recommended, since the file starts in that mode.
Update scylec
Update push.sh to the current setup

I no longer use Dropbox, but Git submodules.

Also, it doesn’t make sense to update the web server if pushing failed.