keyboard-configuration scripts ignores debconf settings if it doesn't
detect an attached keyboard. Instead, it sets XKBOPTIONS to
lv3:ralt_switch, which is not a desired option. It also considers an
empty XKBOPTIONS string to be unset. This workaround sets it to a
placeholder value which is removed later. dpkg-reconfigure is run
so that debconf-get-selections prints the correct values.
* Added Docker support
- replaced necessity for devicemapper (through kpartx) by using parted and
losetup with offsets
- added Dockerfile
- added dependency for parted and grep
- added hints to README.md
- common: loop through unmounts, fix shellcheck warnings
* stage2: use debconf instead of console-setup patch. Fixes#41