Kas

- repos: Silence pycodestyle error (that broke docker image generation)

- Add support for S3 fetcher to docker image
- Lift Python minimal requirements to 3.5
- Fix reporting of of repo patch IDs
- config: use 'qemux86-64' instead of 'qemu' as default for KAS_MACHINE
- Ensure SSH key ends with newline
- kas-docker: Make it harder to run as root
- kas-docker: Make loop device passing optional
- kas-docker: Various fixes

- Add support for Yocto 3.0 / latest Isar
- Move docker image to Debian buster
- Add git-lfs support to docker image
- Add Yocto testimage dependencies to docker image

- Restore mercurial support
- Add -c and --cmd as aliases for --task
- Fix repo patching when using a branch name as refspec
- Update repo remote URL on kas file changes
- kas-docker: fix SHELL forwarding
- kas-docker: use released image, rather than "latest"
- kas-docker: allow to define custom image version
- kasproject/kas: enable devshell and menuconfig targets
- kasproject/kas image: add gnupg and quilt
- kasproject/kas-isar image: fix /var/tmp handling

- isar: Take qemu-user-static from buster and adjust binfmt setup

- kas-docker: Restore KAS_PREMIRRORS support