Features:
+* send out sd_notify() from PID 1 when we determined hostname and machine ID
+
+* send out sd_notify() from PID 1 whenever we reach a target unit. Then
+ introduce ssh.target or so. And in vmspawn/nspawn wait for that as indication
+ whether/when SSH is available. Similar for D-Bus (but just use sockets.target for that)
+
+* teach nspawn/machined a new bus call/verb that gets you a
+ shell in containers that have no sensible pid1, via joining the container,
+ and invoking a shell directly. Then provide another new bus call/vern that is
+ somewhat automatic: if we detect that pid1 is running and fully booted up we
+ provide a proper login shell, otherwise just a joined shell. Then expose that
+ as primary way into the container.
+
+* make vmspawn/nspawn/importd/machined a bit more usable in a WSL-like
+ fashion. i.e. teach unpriv systemd-vmspawn/systemd-nspawn a reasonable
+ --bind-user= behaviour that mounts the calling user through into the
+ machine. Then, ship importd with a small database of well known distro images
+ along with their pinned signature keys. Then add some minimal glue that binds
+ this together: downloads a suitable image if not done so yet, starts it in
+ the bg via vmspawn/nspawn if not done so yet and then requests a shell inside
+ it for the invoking user.
+
* make varlink.h a public API, i.e. give all symbols an sd_ prefix, and rename
header file to sd-varlink.h. This of course also means we have to make json.h
public the same way. Convert the function param checks from assert() to
assert_ret(). Only export the stuff we are sure about, and keep some symbols
internally where things are not clear whether we want other projects to use.
+* machined: allow running in a per-user instance too, to allow unpriv
+ systemd-nspawn and systemd-vmspawn do something useful. (Alternatively: open
+ up system machined to unpriv client's registering their machines, and enforce
+ they come with some prefix or suffix that clarifies they are the
+ user's. i.e. when a user registers a machine it must be called
+ foobar.<username> or so.).
+
+* importd/…: define per-user dirs for container/VM images too.
+
* add a new specifier to unit files that figures out the DDI the unit file is
from, tracing through overlayfs, DM, loopback block device.