0.12

• masked paths use only MS_UNBINDABLE
• mount doesn't specify mount data when there are no options
• support new hook types: createRuntime, createContainer and startContainer
• safer mount options. A temporary mount is prepared outside of the
  rootfs before being moved to it.
• apply selinux/apparmor before the pivot_root.
• handle correctly proc remounts. It is now supported to specify hidepid=
• fix exec if a namespace is not available.
• handle swap limit with the same semantic as on cgroup v1.
• bring network device up.
• reset all signal handlers to default.