A full workflow would look like this:
```sh
./prepare_image.sh && ./mount.sh && sudo ./copy.sh $HOME/.ssh/id_rsa.pub && cp ./setup.sh root/tmp/ && ./chroot.sh && ./umount.sh
```
- prepare_image.sh: loads a fresh raspbian-lite, extracts it and expands
the root partition to ~3.7GB
- mount.sh: mounts the image in rootfs/
- copy.sh: copies some files into the root filesystem, e.g
wpa_supplicant.conf, authorizes SSH key
- setup.sh: updates and installs packages (must be called manually in
chroot)
- chroot.sh: opens a qemu-arm based chroot
- umount.sh: as the name says