Add ability to generate frab.xml from conference and media data

_conferencefrab/nbsp.md

_conferencefrab/nook2022.md

_conferences/nbsp.md

_conferences/nook2022.md

_config.yml

_includes/conference-list.html

_includes/media-list.html

_layouts/conference.html

_layouts/conferences.html

_layouts/frab.xml

_media/2020-12-11-muonpi.md

_media/2022-01-15-i-like-p5.md

_media/2022-05-18-10-jahre.md

_media/2022-12-25-capture-the-flag.md

_media/2023-01-02-aleksis-das-schul-informations-system.md

...023-01-07-linux-user-namespaces-und-der-unshare-befehl.md

_media/2023-01-08-nook22.md

...-14-simon-tathams-portable-puzzle-collection-und-loopy.md

conferences.md