* biboumi: init at 6.1
TODO: integrate config in NixOS
* biboumi: remove external buildtime dep
- fetch catch.hpp in a reproducible way
- add maintainer
- enable tests
- remove git dep
- enable parallel building
- add pandoc dep for man page
- nitpicks
* biboumi: refine substitutions
- only CMakeLists.txt has to be patched regarding /etc/biboumi
- substitute /bin/kill in systemd service file
- prepare for configuring policy_directory in a future cfg file
