copy: use btrfs reflinking only whe we know we copy full files
nspawn: properly unset arg_link_journal_try, when --link-journal= is specified
nspawn: don't link journals in ephemeral mode
nspawn: allow spawning ephemeral nspawn containers based on the root file system of the OS

This works now:

        # systemd-nspawn -xb -D / -M foobar

Which boots up an ephemeral container, based on the host's root file
system. Or in other words: you can now run the very same host OS you
booted your system with also in a container, on top of it, without
having it interfere. Great for testing whether the init system you are
hacking on still boots without reboot the system!
nspawn: when booting in ephemeral mode, append random token to machine name

Also, when booting up an ephemeral container of / use the system
hostname as default machine name.

This way specifiyng -M is unnecessary when booting up an ephemeral
container, while allowing any number of ephemeral containers to run from
the same tree.
man: fedora 21 has been release, suggest 21 as fedora version in example yum command line
update TODO
cap-list: return lower-case capability names, similar to libcap's cap_to_name(), for compat reasons
test-cap-list: always check libcap comes to the same names as we do, for the names it knows
networkctl: show MAC address OUI vendor next to MAC addresses
networkctl: also show gateway address when "networkctl status" without further arguments is passed
networkctl: show interface names next to IP addresses if we dump adresses from all interfaces
networkctl: also draw a nice unicode cirlce when "networkctl status" is run without parameters
core: retry unmounting until we are done, in case of stacked mounts
update TODO
wrap a few *_FOREACH macros in curly braces

cppcheck would give up with "syntax error" without them. This led
to reports of syntax errors in unrelated locations and potentially
hid other errors
networkctl: remove unused variable
hwdb: sort mice by brand,type,dpi,frequency

This way entries from the same brand with the same dpi and frequency
can be coalesced. It is also visually easier to find the right DPI
than order hexadecimal identifiers.
hwdb: add more mice

https://bugs.freedesktop.org/show_bug.cgi?id=87271
shared/hashmap.h: fix comment

An early version used underscore prefixes for internal functions, but
the current version uses the prefix "internal_".