core: the cgroup properties are not actually const
bus: also take write queue into consideration in sd_bus_try_close()
shared: switch our hash table implementation over to SipHash

SipHash appears to be the new gold standard for hashing smaller strings
for hashtables these days, so let's make use of it.
journal: when we shall go down do so cleanly
sd-daemon: introduce sd_watchdog_enabled() for parsing $WATCHDOG_USEC

Also, introduce a new environment variable named $WATCHDOG_PID which
cotnains the PID of the process that is supposed to send the keep-alive
events. This is similar how $LISTEN_FDS and $LISTEN_PID work together,
and protects against confusing processes further down the process tree
due to inherited environment.
systemctl: also color filenames of drop-ins in cat
Fix extraction of _SYSTEMD_USER_UNIT

Units from user services underneath user@.service would not be detected
properly.
loginctl: fix output of type with class
libudev: ship the original MurmurHash2.[ch] file
bus: switch kdbus bloom filter over to SipHash (from MurmurHash3)

Let's try to standardize on a single non-cryptographic hash algorithm,
and for that SipHash appears to be the best answer.

With this change there are two other hash functions left in systemd: an
older version of MurmurHash embedded into libudev for the bloom filters
in udev messages (which is hard to update, given that the we probably
should stay compatible with older versions of the library). And lookup3
in the journal files (which we could replace for new files, but which is
probably not worth the work).
bus: use memcpy() rather than unbounded strcpy()
update TODO
bus-proxyd: synthesize NameAcquire/NameLost signals for socket clients
bus: always talk to the full dbus driver object
bus: make sure to request peer cred only after connect(), not before
delta: fix delta for drop-ins

Also, fix highlighting, add more debug statements, make const tables
static and global, run path_kill_slashes only at entry.
delta: if prefix is specified, only show overrides there

systemd-delta /run/systemd/system will show all unit overrides
in /run, etc.
bus: write debug message when we get a method call we cannot handle
bus: make sure sd_bus_emit_properties_changed_strv() doesn't return ENOENT if no properties with a change flag are in the interface
log: als turn on debug logging in non-PID1 if /proc/cmdline contains "debug"