Last commit made the script break on macOS.
From `man sed` (On Linux):
```
-E, -r, --regexp-extended
use extended regular expressions in the script (for portability use POSIX -E).
```
* bash variables in build-docker.sh are wrapped by curly brackets
* Ensure presence of config file while running build-docker.sh
* Do not assume that build-docker.sh is run from the repository root directory
* Mount config file in predictable location in docker container
* SC1091: the `config` file might not be present, which is normal.
* SC2086: Double quote to prevent globbing and word splitting.
Tested clean output using: `find -name "*.sh" -exec shellcheck -x {} \;`
* Made more specific shellcheck disables
* Fixed variable quoting (SC2086,SC2064)
* Use `$*` expansion instead of `$@` when not using arrays (SC2124)
* Use cleaner `$()` syntax instead of back quotes (SC2006)
* Improved comparator (SC2166)
* Minor improvements in coding style
Tested clean output using: `find -name "*.sh" | xargs -n1 shellcheck -x`.
Fixes#253
Rather than use --env-file, which gets overwritten by the regular config file, pass the any arguments to build-docker.sh through to build.sh.
* 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
