bus: fix typo

Drop spurious 'we'.
core: loopback - correctly fail the loopback_check if somehow the rtnl calls fail
capability: use /proc/sys/kernel/cap_last_cap

This file was introduced with linux-3.2, use it instead of probing for it
via prctl(PR_CAPBSET_READ).

For now, keep the old code for backwards compat. We can drop it once 3.2
is our lowest requirement.

The test-cap-list code is extended to verify cap_last_cap() is the same as
we'd get via prctl probing and /proc.
bus-proxy: fix sd_bus_reply_*() usage

We *must* not use sd_bus_reply_*() as it does not set the sender field
correctly. Use the synthetic_reply_*() helpers instead!
units: make graphical.target dependencies more complete and similar to those of multi-user.target
units: rework systemd-nspawn@.service unit

- Unescape instance name so that we can take almost anything as instance
  name.

- Introduce "machines.target" which consists of all enabled nspawns and
  can be used to start/stop them altogether

- Look for container directory using -M instead of harcoding the path in
  /var/lib/container
machinectl: add new "start" verb to start a container as a service in nspawn
machinectl: add "enable" and "disable" verbs for enabling/disabling systemd-nspawn for containers

This is basically just a shortcut for "systemctl enable
systemd-nspawn@<foobar>.service", but does escaping.
Update TODO
preset: enable machines.target by default
nspawn: report back to systemd only very late whether we are OK

That way, systemd can actually figure out if everything is OK with
nspawn.
machined: ignore spurious error
Revert "machined: don't force terminate registered machines"

This reverts commit 206e7a5f7b55ac61188efd895e65ab26e478cbb2.

We actually want to allow shutting down containers that use
RegisterMachine() rather than CreateMachine() to register their own
unit. It should be safe to do so, since the primary usecase for
RegisterMachine() are container managers that run only a single
container within their own unit, such as systemd-nspawn.
update TODO
hwdb: Update database of Bluetooth company identifiers
macro: add DIV_ROUND_UP()

This macro calculates A / B but rounds up instead of down. We explicitly
do *NOT* use:
        (A + B - 1) / A
as it suffers from an integer overflow, even though the passed values are
properly tested against overflow. Our test-cases show this behavior.

Instead, we use:
        A / B + !!(A % B)

Note that on "Real CPUs" this does *NOT* result in two divisions. Instead,
instructions like idivl@x86 provide both, the quotient and the remainder.
Therefore, both algorithms should perform equally well (I didn't verify
this, though).